Kovic was born in Ladysmith, Wisconsin, the second eldest of the six children of Patricia Lamb and Eli Kovic. He was raised in Massapequa, New York, in a Roman Catholic household. His Father of Croatian descent served honorably in the United States Navy during World War II. He met Lamb during the Second World War when she was serving in the United States Navy to which she enlisted not long after Pearl Harbor, December 7, 1941. She was of Irish ancestry, and a housewife. After the war, Eli Kovic and his family moved to Levittown, New York, where he worked as a grocery clerk in an A&P food store. In high school, Ron Kovic was a Wrestler and pole vaulter, and hoped to be a major league baseball player after graduation.

Inspired by President John F. Kennedy's "Ask not what your country can do for you; ask what you can do for your country" Inaugural Address in January 1961 and after Kennedy's death in November 1963, Kovic joined the United States Marine Corps after high school in September 1964. He was sent to the Marine Corps Recruit Depot Parris Island, South Carolina, where, after twelve weeks' intensive recruit training, he was promoted to the rank of Private First Class and became the push-up champion of his battalion. Kovic was then sent to the Infantry Training Regiment (ITR) at Camp Lejeune, North Carolina, for advanced combat training. He returned home to Massapequa just before Christmas in December. After several weeks' leave, Kovic was assigned to the Marine Corps Barracks at Norfolk, Virginia, where he attended radio school and learned communication skills, including Morse code. He was next assigned to the Second Field Artillery Battalion, Camp Lejeune, North Carolina.

In a new introduction to his book, Born on the Fourth of July (1976), written in March 2005, Kovic stated, "I wanted people to understand. I wanted to share with them as nakedly and openly and intimately as possible what I had gone through, what I had endured. I wanted them to know what it really meant to be in a war, to be shot and wounded, to be fighting for my life on the intensive care ward, not the myth we had grown up believing. I wanted people to know about the hospitals and the enema room, about why I had become opposed to the war, why I had grown more and more committed to peace and nonviolence. I had been beaten by the police and arrested twelve times for protesting the war and I had spent many nights in jail in my wheelchair. I had been called a Communist and a traitor, simply for trying to tell the truth about what had happened in that war, but I refused to be intimidated." In 1989, Kovic presented actor Tom Cruise (born July 3, 1962) who portrayed him in the movie Born On The Fourth of July, on the last day of filming, the original Bronze Star Medal he had received, explaining to Cruise that he was giving him the medal as a gift "for his heroic performance." Time magazine reported that Oliver Stone said, "He gave it to Tom for bravery for having gone through this experience in hell as much as any person can without actually having been there."

He was assigned to H&S Company, 1st Amtrac Battalion (1st Amphibian Tractor Battalion), 3rd Marine Division in South Vietnam. In October 1967, according to Kovic's own account, he shot and killed another Marine by accident during a North Vietnamese Army (NVA) ambush near a village along the Cua Viet River.

On January 20, 1968, while leading a reconnaissance force of battalion scouts from the 1st Amtrac Battalion just north of the Cua Viet River in the vicinity of the village of My LOC, in the Demilitarized Zone, Kovic's squad came into contact with the 803rd NVA Regiment and elements of a Viet Cong battalion that was besieging the village, and he was shot by North Vietnamese Soldiers while leading his rifle squad across an open area, attempting to aid the South Vietnamese Popular Force unit in the village. Deserted by most of his unit, he was shot first in the right foot, which tore out the back of his heel, then again through the right shoulder, suffering a collapsed lung and a spinal cord injury that left him paralyzed from the chest down. The first Marine that tried to save him was shot through the heart and killed, then a second Marine carried Kovic to safety through heavy enemy fire. Kovic then spent a week in an intensive care ward in Da Nang. As a result of his Service and injuries in the conflict, Kovic was awarded the Bronze Star Medal with Combat "V" for heroism in battle and the Purple Heart Medal.

Undeterred, Kovic continued speaking to students from the school's football grandstands. His first arrest was during an anti-Vietnam War demonstration at an Orange County, California draft board in the spring of 1971 when he refused to leave the office of the draft board explaining to a representative that, by sending young men to Vietnam, they were inadvertently "condemning them to their death," or to be wounded and maimed like himself in a war that he had come to believe was, "immoral and made no sense." He was told that, if he did not leave the draft board immediately, he would be arrested. Kovic refused to leave, and was taken away by police.

In 1974, Kovic led a group of disabled Vietnam War veterans in wheelchairs on a 17-day hunger strike inside the Los Angeles office of Senator Alan Cranston. The veterans protested the "poor treatment in America's Veterans Hospitals" and demanded better treatment for returning veterans, a full investigation of all Veterans Administration (VA) facilities, and a face-to-face meeting with head of the VA, Donald E. Johnson. The strike continued to escalate until Johnson finally agreed to fly out from Washington, D.C., and meet with the veterans. The hunger strike ended soon after that. Several months later Johnson resigned. In late August 1974, Kovic traveled to Belfast, Northern Ireland, where he spent a week in the Catholic stronghold of "Turf Lodge," interviewing both political Activists and residents. In the spring of 1975 Kovic, author Richard Boyle, and photo Journalist Loretta Smith traveled to cover the war in Cambodia for Pacific News Service.

Before the war in Vietnam was declared ended on April 30, 1975, Kovic became one of the best-known peace Activists among the Vietnam veterans and was arrested 12 times for political protesting. He attended his first peace demonstration soon after the Kent State shootings in May 1970, and gave his first speech against the war at Levittown Memorial High School in Levittown, Long Island, New York that same spring. Kovic's speech that day was interrupted by a bomb threat and the auditorium cleared.

Bruce Springsteen wrote the song "Shut Out the Light" after reading Kovic's memoir and then meeting him. Tom Paxton, the folk singer/political Activist, wrote the song "Born on the Fourth of July", which is on his 1977 New Songs from the Briarpatch album, and met Kovic backstage at the Bottom Line Club in New York City the same year. Academy Award-winning Actress Jane Fonda has stated that Ron Kovic's story was the inspiration for the 1978 Vietnam War film Coming Home in which she starred.

From 1990 to 1991, Kovic took part in several anti-war demonstrations against the first Gulf War, which occurred not long after the release of his biographical film in 1989. In early May 1999, following the U.S. bombing of the Chinese embassy in Belgrade, Yugoslavia, Kovic met with China's ambassador to the United States Li Zhaoxing at the Chinese embassy in Washington D.C. to express his most sincere condolences and present the ambassador and his staff with two dozen red roses. He was an outspoken critic of the Iraq War.

In March 2007, Kovic checked into the Ernest Bors Spinal Cord Injury ward of the Veterans Administration Hospital in Long Beach, California, for an undisclosed illness.

On January 20, 2008, Kovic observed his 40th anniversary of having been shot and paralyzed in the Vietnam War. Kovic, in March 2005, said: "The scar will always be there, a living reminder of that war, but it has also become something beautiful now, something of faith and hope and love. I have been given the opportunity to move through that dark night of the soul to a new shore, to gain an understanding, a knowledge, and entirely different vision. I now believe I have suffered for a reason and in many ways I have found that reason in my commitment to peace and nonviolence. My life has been a blessing in disguise, even with the pain and great difficulty that my physical disability continues to bring. It is a blessing to speak on behalf of peace, to be able to reach such a great number of people."

On April 8, 2009, Kovic joined British MP George Galloway to launch Viva Palestina USA, an American branch of Viva Palestina. Kovic planned to co-lead with Galloway a humanitarian relief convoy to the Gaza Strip in early July 2009. On December 6, 2009 Kovic spoke honoring Bruce Springsteen at the 32nd annual Kennedy Center Honors in Washington, D.C. On December 22, 2009, Kovic, Oliver Stone, and friends celebrated the 20th anniversary of the 1989 film release of Born on the Fourth of July at a dinner party in Torrance, California. In April 2010, Kovic traveled to Rome, Italy, as a member of the Council for Dignity, Forgiveness, and Reconciliation. Between April 19–26, he attended meetings at Rome's City Hall with other international peace Activists, diplomats and academics, to discuss the need for conflict resolution and other more peaceful, nonviolent alternatives to war as a way of solving the world's many conflicts. On April 21, 2010, he spoke of his journey from war to peace, forgiveness, and reconciliation before Rome's mayor Gianni Alemanno, and other civic Leaders at Rome's Ara Pacis (Altar of Augustan Peace), commissioned by the Roman Senate July 4, 13 BC.

On July 4, 2016 Akashic Books published the 40th anniversary edition of Born on the Fourth of July, with a foreword by Bruce Springsteen, in conjunction with Kovic's latest book, Hurricane Street. Naming it a Top 10 Pick for Spring 2016, Publishers Weekly reported, “The author of the bestseller Born on the Fourth of July writes an impassioned and timely memoir about the 1974 American Veterans Movement that will strike a chord with veterans and their families today.” On January 20, 2018 Ron Kovic observed the 50th anniversary of having been shot and paralyzed in the Vietnam War.