John Van Buren was born on February 18, 1810 in Hudson, Columbia County, New York. He graduated from Yale College in 1828 and studied law with Benjamin F. Butler. He was admitted to the New York state bar in 1830. In 1831, when Martin Van Buren was appointed U.S. Minister to Britain, John Van Buren accompanied his father to London, serving as secretary of the American Legation there. He returned home in 1832 after Congress failed to confirm his father's appointment.
When he returned home, John Van Buren opened a law practice with James McKown in Albany. Contemporaries recalled that John had a remarkable memory and had a successful law practice earned by his ability as much as his family connections. He returned to England on his own in 1838 during his father's Presidency, where he attended Queen Victoria's coronation. He was given the nickname of “Prince John” after he danced with her in 1838. His tour of Europe gained notoriety as he dined with the who’s who of 19th century England, Ireland and Scotland. He also met the King of France, Louis Philippe I, the King of Belgium, Leopold I, and the King of the Netherlands, William I.
On June 22, 1841, John Van Buren married Elizabeth Vanderpoel, his childhood sweetheart. They had one daughter, Anna (1842-1923). Like his father, he became a widow when his wife died in 1844, three years after their marriage. After her death, he never remarried.
From 1845 to 1847, he served as New York State Attorney General. In 1845, he conducted the prosecution of some leaders of the Anti-Rent War at their trial for riot, conspiracy and robbery. At the first trial the jury was deadlocked. At the re-trial, in September 1845, he got into a fist-fight in open court with his opposing counsel Ambrose Jordan, and the two lawyers were sentenced by the presiding judge, Justice John W. Edmonds, to "solitary confinement in the county jail for 24 hours." After that Van Buren offered to resign, but Governor Silas Wright refused to accept his resignation. Both counsel continued with the case after their release. The defendant, Smith A. Boughton, was sentenced to life imprisonment. At the next state election Governor Wright was defeated by John Young, who had the support of the Anti-Renters. Young pardoned Boughton.
John Van Buren also prosecuted the case of William Freeman, who murdered four members of the Van Nest family of Cayuga County, New York on March 12, 1846. The lead defense counsel was future Secretary of State William H. Seward. The defense tried to mount a defense of insanity (i.e. that their client was mentally unfit to stand trial), but a local jury disagreed and the trial began after days of jury selection. Because it was a capital case, Quakers (Anti-death penalty) were dismissed from the jury panel. Van Buren vigorously contested the defense’s insanity strategy. In his addresses to the jury, he explained the cause and effect of finding Freeman guilty. The prosecution did everything they could to show the jury that Freeman was in fact sane and should be found guilty and face the death penalty. Race was a huge factor in the case. Freeman's mother was Native American and his father was African-American. His lawyers argued he was a product of the mixing of two inferior races and that this was one reason for his insanity. At a time when racism was common, these claims were considered by the jury, who deliberated for two hours before finding Freeman guilty on July 23, 1846. The next day, William Freeman was sentenced by Judge Whiting to hang. But in in January 1847, however, the Supreme Court reversed the decision and granted Freeman a new trial. Freeman died on August 21, 1847 of tuberculosis in his jail cell, weeks before the new trial was to begin.
Later in 1847, Van Buren moved to New York City and formed a partnership with Hamilton W. Robinson. Van Buren was counsel in a lawsuit for the divorce of Edwin Forrest, a famous actor. He was asked to run for various offices but always declined.
In 1848, Van Buren was the leader of the Barnburner faction of the Democratic Party, which repudiated the 1848 Democratic National Convention held in Baltimore. The Barnburners met for a State Convention in Utica, New York on June 22 and nominated Van Buren's father as their presidential candidate. (Another son of a President was on the ticket as his father's running mate: Charles Francis Adams, son of John Quincy Adams). On August 9, the National Convention of the Free Soil Party, held at Buffalo, New York, endorsed this nomination. Lewis Cass ended up on the official Democratic ticket. Martin Van Buren failed to win a single state and Zachary Taylor won the presidency. Martin Van Buren’s votes in New York likely cost Cass the election. In the campaign, John Van Buren was credited with the saying, "Vote early and vote often".
In 1865, John Van Buren again ran for the office of New York state Attorney General on the Democratic ticket, but was defeated by Republican John H. Martindale. After Van Buren's defeat, he visited Europe in 1866 accompanied by his daughter and niece. They traveled to England, Sweden, Norway and Russia.
On October 13, 1866, John Van Buren died from exposure on the return journey from Liverpool to New York City aboard the ship Scotia. He was 56 years old. Sailors wanted to cast his body into the sea, but the captain would not allow it. After the ship arrived in New York, funeral services were held at that city's Grace Church and in Albany's St. Peter's Church. John Van Buren's grave is located in the Albany Rural Cemetery.