Hunt was educated at home. As a teenager, Hunt traveled to various places before settling in Arkansas, where he was running a cotton plantation by 1912. He had a reputation as a math Prodigy and was a gambler. It was said that after his cotton plantation was flooded, he turned his last $100 into more than $100,000, gambling in New Orleans. With his winnings, he purchased oil properties in the neighborhood of El Dorado, Arkansas. He was generous to his employees, who in turn were loyal to him, informing him of rumors of a massive oil field to the south, in East Texas—the East Texas Oil Field. In negotiations over cheese and crackers, at the Adolphus Hotel in Dallas, with the wild-catter who discovered the field—"Dad" Joiner—Hunt secured title to what was then the largest known oil deposit in the world, having agreed to pay only $1,000,000, and protect Mr. Joiner from liability for his many fraudulent transactions surrounding the property. In 1957 Fortune estimated that Hunt had a fortune of between U.S. $400 million and $700 million ($4.5 billion in 2011, adjusted for inflation), and was one of the eight richest people in the United States. J. Paul Getty, who was considered at the time to be the richest private citizen in the world, said of Hunt: "In terms of extraordinary, independent wealth, there is only one man—H. L. Hunt."

He married Lyda Bunker of Lake Village, Arkansas in November 1914, and remained married to her until her death in 1955. His seven children by her were: Margaret (1915-2007), Haroldson ("Hassie," 1917-2005), Caroline (1923), Lyda (born and died in 1925), Nelson Bunker (1926-2014), william Herbert (1929), and Lamar (1932-2006). Their home on White Rock Lake in Dallas was styled after Mount Vernon though much larger.

While still married to Lyda, H. L. Hunt is said to have married Frania Tye of Tampa, Florida in November 1925, using the name Franklin Hunt. Frania claimed to have discovered the bigamous nature of her marriage in 1934, and in a legal settlement in 1941, Hunt created trust funds for each of their four children and she signed a document stipulating that no legal marriage between them had ever existed. About the same time, she briefly married then divorced Hunt's employee, John Lee, taking the last name Lee for herself and her four children. Her four children by Hunt were: Howard (born 1926), Haroldina (1928), Helen (1930), and Hugh ("Hue," 1934). Frania Tye Lee died in 2002.

Hunt supported and had children by Ruth Ray of Shreveport, Louisiana, whom he met when she was a secretary in his Shreveport office. They married in 1957 after the death of Hunt's wife Lyda. His four children by her were: Ray (born 1943), June (1944), Helen (1949), and Swanee (1950). His youngest son, Ray Lee, ultimately inherited the Business, and was a major supporter of President George W. Bush.

A scandal emerged in 1975, after his death, when it was discovered that he had had a hidden bigamous relationship, with his second wife living in New York. Nonetheless, Hunt was a member of the First Baptist Church of Dallas, and was a major financial contributor toward the establishment of the conservative Christian evangelical Criswell College in Dallas, Texas.