Velázquez was born in Seville, Spain, the first child of João Rodrigues de Silva and Jerónima Velázquez, and was baptized at the church of St. Peter in Seville on Sunday, June 6, 1599. The christening most likely occurred a few days or weeks after his birth. His paternal grandparents, Diogo da Silva and Maria Rodrigues, had moved to Seville from their native Portugal decades earlier. When Velázquez was offered knighthood in 1658, he claimed descent from the lesser nobility in order to qualify; in fact, however, his grandparents were tradespeople, and possibly Jewish conversos.

By the early 1620s, his position and reputation were assured in Seville. On April 23, 1618, Velázquez married Juana Pacheco (June 1, 1602 – August 10, 1660), the daughter of his Teacher. She bore him two daughters—his only known family. The elder, Francisca de Silva Velázquez y Pacheco (1619–1658), married Painter Juan Bautista Martínez del Mazo at the Church of Santiago in Madrid on August 21, 1633; the younger, Ignacia de Silva Velázquez y Pacheco, born in 1621, died in infancy.

Velázquez, through his daughter Francisca de Silva Velázquez y Pacheco (1619–1658), is an ancestor of the Marquesses of Monteleone, including Enriquetta (Henrietta) Casado de Monteleone (1725–1761) who in 1746 married Heinrich VI, Count Reuss zu Köstritz (1707–1783). Through them are descended a number of European royalty, among them Queen Sofía of Spain, Queen Beatrix of the Netherlands, King Carl XVI Gustaf of Sweden, King Albert II of Belgium, Hans-Adam II, Prince of Liechtenstein, and Henri, Grand Duke of Luxembourg.

Velázquez went to Madrid in the first half of April 1622, with letters of introduction to Don Juan de Fonseca, himself from Seville, who was chaplain to the King. At the request of Pacheco, Velázquez painted the portrait of the famous poet Luis de Góngora. Velázquez painted Góngora crowned with a laurel wreath, but painted over it at some unknown later date. It is possible that Velázquez stopped in Toledo on his way from Seville, on the advice of Pacheco, or back from Madrid on that of Góngora, a great admirer of El Greco, having composed a poem on the occasion of his death.

Through the bust portrait of the king, painted in 1623, Velázquez secured admission to the royal Service, with a salary of 20 ducats per month, besides medical attendance, lodgings and payment for the pictures he might paint. The portrait was exhibited on the steps of San Felipe and was received with enthusiasm. It is now lost. The Museo del Prado, however, has two of Velázquez's portraits of the king (nos. 1070 and 1071) in which the severity of the Seville period has disappeared and the tones are more delicate. The modeling is firm, recalling that of Antonio Mor, the Dutch portrait Painter of Philip II, who exercised a considerable influence on the Spanish school. In the same year, the Prince of Wales (afterwards Charles I) arrived at the court of Spain. Records indicate that he sat for Velázquez, but the picture is now lost. In September 1628, Peter Paul Rubens came to Madrid as an emissary from the Infanta Isabella, and Velázquez accompanied him to view the Titians at the Escorial. Rubens was then at the height of his powers. The seven months of the diplomatic mission showed Rubens' brilliance as Painter and courtier. Rubens had a high opinion of Velázquez, but he had no significant influence on his painting. He reinforced Velázquez's Desire to see Italy and the works of the great Italian masters.

In 1627, Philip set a competition for the best Painters of Spain with the subject to be the expulsion of the Moors. Velázquez won. His picture was destroyed in a fire at the palace in 1734. Recorded descriptions of it say that it depicted Philip III pointing with his baton to a crowd of men and women being led away by Soldiers, while the female personification of Spain sits in calm repose. Velázquez was appointed gentleman usher as reward. Later he also received a daily allowance of 12 réis, the same amount allotted to the court barbers, and 90 ducats a year for dress. Five years after he painted it in 1629, as an extra payment, he received 100 ducats for the picture of Bacchus (The Triumph of Bacchus). The spirit and aim of this work are better understood from its alternate Spanish name, Los Borrachos (The Drunks) or Los Bebedores (the drinkers), who are paying mock homage to a half-naked ivy-crowned young man seated on a wine barrel. The painting is firm and solid, and the light and shade are more deftly handled than in former works. Altogether, this production may be taken as the most advanced Example of the first style of Velázquez.

In 1629, Velázquez went to live in Italy for a year and a half. Though his first Italian visit is recognized as a crucial chapter in the development of his style—and in the history of Spanish Royal Patronage, since Philip IV sponsored his trip—few details and specifics are known of what the Painter saw, whom he met, how he was perceived and what innovations he hoped to introduce into his painting. It is canonical to divide the artistic career of Velázquez by his two visits to Italy, with his second grouping of works following the first visit and his third grouping following the second visit. This somewhat arbitrary division may be accepted though it will not always apply, because, as is usual in the case of many Painters, his styles at times overlap each other. Velázquez rarely signed his pictures, and the royal archives give the dates of only his most important works. Internal evidence and history pertaining to his portraits supply the rest to a certain extent.

The greatest of the religious paintings by Velázquez also belongs to this middle period, the Christ Crucified (1632). It is a work of tremendous originality, depicting Christ immediately after death. The Savior's head hangs on his breast and a mass of dark tangled hair conceals part of the face. The figure stands alone. The picture was lengthened to suit its place in an oratory, but this addition has since been removed. Some believe that the man in this painting is his uncle.

Velázquez's son-in-law Juan Bautista Martinez del Mazo had succeeded him as usher in 1634, and Mazo himself had received a steady promotion in the royal household. Mazo received a pension of 500 ducats in 1640, increased to 700 in 1648, for portraits painted and to be painted, and was appointed inspector of works in the palace in 1647.

The Sculptor Juan Martínez Montañés modeled a statue on one of Velázquez's Equestrian portraits of the king, painted in 1636, which was cast in bronze by the Florentine Sculptor Pietro Tacca and which now stands in the Plaza de Oriente at Madrid. The original of this portrait no longer exists, but several others do. Velázquez, in this and in all his portraits of the king, depicts Philip wearing the golilla, a stiff linen collar projecting at right angles from the neck. It was invented by the king, who was so proud of it that he celebrated it by a festival followed by a procession to the church to thank God for the blessing. Thus, the golilla was the height of fashion and appeared in most of the male portraits of the period.

Velázquez was in constant and close attendance on Philip, accompanying him in his journeys to Aragon in 1642 and 1644, and was doubtless present with him when he entered Lerida as a conqueror. It was then that he painted a great Equestrian portrait in which the king is represented as a great commander leading his troops—a role that Philip never played except in pageantry. All is full of animation except the stolid face of the king. It hangs as a pendant to the great Olivares portrait—fit rivals of the neighboring Charles V by Titian, which inspired Velázquez to excel himself, and both remarkable for their silvery tone and their feeling of open air.

Had it not been for this royal appointment, which enabled Velázquez to escape the censorship of the Inquisition, he would not have been able to release his La Venus del espejo (c. 1644–1648, English: Venus at her Mirror) also known as The Rokeby Venus. It is the only surviving female nude by Velázquez.

Velázquez then painted the first of many portraits of the young Prince and heir to the Spanish throne, Don Baltasar Carlos, looking dignified and lordly even in his childhood, in the dress of a field marshal on his prancing steed. The scene is in the riding school of the palace, the king and queen looking on from a balcony, while Olivares attends as master of the horse to the Prince. Don Baltasar died in 1646 at the age of seventeen, so, judging by his age in the portrait, it must have been painted in about 1641.

When he set out in 1649, he was accompanied by his assistant Juan de Pareja who at this point in time was a slave and who had been trained in painting by Velázquez. Velázquez sailed from Málaga, landed at Genoa, and proceeded from Milan to Venice, buying paintings of Titian, Tintoretto and Veronese as he went. At Modena he was received with much favor by the duke, and here he painted the portrait of the duke at the Modena gallery and two portraits that now adorn the Dresden gallery, for these paintings came from the Modena sale of 1746.

In 1650 in Rome Velázquez also painted a portrait of Juan de Pareja, now in the Metropolitan Museum of Art in New York City, USA. This portrait procured his election into the Academy of St. Luke. Purportedly Velázquez created this portrait as a warm-up of his skills before his portrait of the Pope. It captures in great detail Pareja's countenance and his somewhat worn and patched clothing with an economic use of brushwork. In November 1650, Juan de Pareja was freed by Velázquez. The legal document exists.

King Philip wished that Velázquez return to Spain; accordingly, after a visit to Naples, where he saw his old friend Jose Ribera, he returned to Spain via Barcelona in 1651, taking with him many pictures and 300 pieces of statuary, which afterwards were arranged and catalogued for the king. Undraped sculpture was, however, abhorrent to the Spanish Church, and after Philip's death these works gradually disappeared. Elisabeth of France had died in 1644, and the king had married Mariana of Austria, whom Velázquez now painted in many attitudes. He was specially chosen by the king to fill the high office of aposentador mayor, which imposed on him the duty of looking after the quarters occupied by the court—a responsible function which was no sinecure and one which interfered with the exercise of his art. Yet far from indicating any decline, his works of this period are amongst the highest examples of his style.

One of the infantas, Margaret Theresa, the eldest daughter of the new Queen, appears to be the subject of Las Meninas (1656, English: The Maids of Honour), Velázquez's magnum opus. However, in looking at the various viewpoints of the painting it is unclear as to who or what is the true subject. Is it the royal daughter, or perhaps the Painter himself? The answer may lie in the image on the back wall, depicting the King and Queen. Is this image a mirror, in which case the King and Queen are standing where the spectator stands? Are they the subject of Velázquez's work? Or is the work simply a court painting?

One of his final works was Las hilanderas (The Spinners), painted circa 1657, representing either the interior of the royal tapestry works or a depiction of Ovid's Fable of Arachne, depending on interpretation. The tapestry in the background is based on Titian's The Rape of Europa, or, more probably, the copy that Rubens painted in Madrid. It is full of light, air and movement, featuring vibrant colors and careful handling. Anton Raphael Mengs said this work seemed to have been painted not by the hand but by the pure force of will. It displays a concentration of all the art-knowledge Velázquez had gathered during his long artistic career of more than forty years. The scheme is simple—a confluence of varied and blended red, bluish-green, gray and black.

In 1660 a peace treaty between France and Spain was consummated by the marriage of Maria Theresa with Louis XIV, and the ceremony took place on the Island of Pheasants, a small swampy island in the Bidassoa. Velázquez was charged with the decoration of the Spanish pavilion and with the entire scenic display. He attracted much attention from the nobility of his bearing and the splendor of his costume. On June 26 he returned to Madrid, and on July 31 he was stricken with fever. Feeling his end approaching, he signed his will, appointing as his sole executors his wife and his firm friend named Fuensalida, keeper of the royal records. He died on August 6, 1660. He was buried in the Fuensalida vault of the church of San Juan Bautista, and within eight days his wife Juana was buried beside him. Unfortunately, this church was destroyed by the French in 1811, so his place of interment is now unknown. There was much difficulty in adjusting the tangled accounts outstanding between Velázquez and the treasury, and it was not until 1666, after the death of King Philip, that they were finally settled.

Until the nineteenth century, little was known outside of Spain of Velázquez's work. His paintings mostly escaped being stolen by the French Marshals during the Peninsular War. In 1828 Sir David Wilkie wrote from Madrid that he felt himself in the presence of a new power in art as he looked at the works of Velázquez, and at the same time found a wonderful affinity between this Artist and the British school of portrait Painters, especially Henry Raeburn. He was struck by the modern impression pervading Velázquez's work in both landscape and portraiture. Presently, his technique and individuality have earned Velázquez a prominent position in the annals of European art, and he is often considered a father of the Spanish school of art. Although acquainted with all the Italian schools and a friend of the foremost Painters of his day, he was strong enough to withstand external influences and work out for himself the development of his own nature and his own principles of art.

The Anglo-Irish Painter Francis Bacon found Velázquez's portrait of Pope Innocent X to be one of the greatest portraits ever made. He created several expressionist variations of this piece in the 1950s; however, Bacon's paintings presented a more gruesome image of the pope, who had now been dead for centuries. One such famous variation, entitled Figure with Meat (1954), shows the pope between two halves of a bisected cow.

The importance of Velázquez's art even today is evident in considering the respect with which twentieth century Painters regard his work. Pablo Picasso presented the most durable homages to Velázquez in 1957 when he recreated Las Meninas in 58 variations, in his characteristically cubist form. Although Picasso was concerned that his reinterpretations of Velázquez's painting would be seen merely as copies rather than unique representations, the enormous works—including the largest he had produced since Guernica in 1937—obtained a position of importance in the canon of Spanish art. Picasso retained the general form and positioning of the original in the context of its avant-garde cubist style.

Salvador Dalí, as with Picasso in anticipation of the tercentennial of Velázquez's death, created in 1958 a work entitled Velázquez Painting the Infanta Margarita With the Lights and Shadows of His Own Glory. The color scheme shows Dalí's serious tribute to Velázquez; the work also functioned, as in Picasso's case, as a vehicle for the presentation of newer theories in art and thought—nuclear mysticism, in Dalí's case.

In the 1966 book Les Mots et Les Choses (The Order of Things), Philosopher Michel Foucault devotes the opening chapter to a detailed analysis of Las Meninas. He describes the ways in which the painting problematizes issues of representation through its use of mirrors, screens, and the subsequent oscillations that occur between the image's interior, surface, and exterior. In his book, The Dying Animal, Philip Roth uses Las Meninas as a metaphor for the distracted attraction of courtship.

Spain's celebration of the 400th anniversary of Velázquez's birth included major exhibitions of his work at the Prado Museum, as well as a renewed search for his tomb. International media covered the dig, which began April 30, 1999, at the Plaza de Ramales, one block from the Royal Palace, because that is where the medieval Church of San Juan stood until it was wrecked during the last century. In early 2000, The Telegraph announced that the search for Velázquez's body would be abandoned: "A CAR park is to be built over what is widely believed to be the site of the tomb of Velázquez, one of Spain's greatest artists, after the authorities abandoned attempts to find his body...thought to have been buried in Madrid at the Iglesia de San Juan Bautista. For 18 months the authorities have been excavating the site of the church which is buried under a residential area. But now they have bowed to residents' demands for underground parking."

In 2009, the Portrait of a Man in the collection of the Metropolitan Museum of Art, which had long been associated with the followers of Velázquez' style of painting, was cleaned and restored. It was found to be by Velázquez himself, and the features of the man match those of a figure in the painting "the Surrender of Breda". The newly cleaned canvas may therefore be a study for that painting. Although the attribution to Velázquez is regarded as certain, the identity of the sitter is still open to question. Some art historians regard this new study to be a self-portrait by Velázquez.

In 2010 it was reported that a damaged painting long relegated to a basement of the Yale University Art Gallery might be an early work by Velázquez. Thought to have been given to Yale in 1925, the painting has previously been attributed to the 17th-century Spanish school. Some scholars are prepared to attribute the painting to Velázquez, though the Prado Museum in Madrid is reserving judgment. The work, which depicts the Virgin Mary being taught to read, will be restored by conservators at Yale.

In October 2011 it was confirmed by art Historian Dr. Peter Cherry of Trinity College Dublin through x-ray analysis that a portrait found in the UK in the former collection of the 19th-century Painter Matthew Shepperson is a previously unknown work by Velázquez. The portrait is of an unidentified man in his fifties or sixties, who could possibly be Juan Mateos, the Master of the Hunt for Velázquez's patron, King Philip IV of Spain. The painting measures 47 x 39 cm and was sold at auction on December 7, 2011, for £3,000,000.

There were essentially only two patrons of art in Spain—the church and the art-loving king and court. Bartolomé Esteban Murillo was the Artist favored by the church, while Velázquez was patronized by the crown. One difference, however, deserves to be noted. Murillo, who toiled for a rich and powerful church, left little means to pay for his burial, while Velázquez lived and died in the enjoyment of a good salary and pension.