As a child, John was born with a condition called spina bifida, for which was corrected by a surgeon when he was still an infant. Ever since his childhood, he had a passion for music. At a very young age of fourteen, he established his first band, Crepe Soul, and later played in the local bands Trash, Snakepit Banana Barn and the Mason Brothers. He also worked with many local bands and later, he got a job in Seymour Telephone Installations. Certainly, doing a job in a telephone installation firm, was not enough for Mr Mellencamp.  Therefore, he decided to pursue his musical career and came to New York, hoping to get a music contract. Initially, John had to face many failures. However, when his album “The Kid Inside” was launched, it got great response from fans and critics alike.

John decided to get married to his girlfriend Priscilla Esterline, when he was just eighteen, while she was expecting a baby, and became a father three months after he completed high school. Michelle Mellencamp, daughter of John Mellencamp became a mother when she was 19 years old making John, a grandfather, when he turned 37.

He first got married to Priscilla Esterline in 1970 and they got divorced in 1981. He has two daughters from his second marriage with Victoria Granucci from the 8 years of relationship as a couple. Later, he had two sons from Elaine Irwin, who was a model.  John and Elaine had a relationship as husband and wife for 18 years, which broke up, resulting in a divorce. Their divorce became official on August 12, 2011, with the couple negotiating "an amicable settlement of all issues involving property and maintenance rights, the custody and support of their children, and all other issues", according to the settlement agreement.

John has five children in total from a result of his three marriages. His daughter Michelle with his ex wife Priscilla Esterline, daughters Teddi Jo and Justice his ex wife Victoria Granucci, and sons Hud and Speck with his ex wife Elaine Irwin. 

Controversies have always been inseparable part of John Mellencamp’s life. He also had an extra marital affair going on with actress Meg Ryan, which officially became public after he got a divorce from his third wife. Meg Ryan was married to actor Dennis Quaid and they have a son. She and her husband sought a divorce in 2011. The two seem to have a on and off again relationship. It was reported in the media that John Mellencamp and Meg Ryan stopped seeing each other in the summer of 2014, after dating for over three years. But in October 2014, it was revealed that Mellencamp and Ryan were back together once again. In the summer of 2015, it was reported they broke up again.

In September 2015, Mellencamp began a new relationship with former supermodel Christie Brinkley. In August 2016, the couple announced their separation after almost a year of dating. To no ones surprise, in July 2017 it was reported Mellencamp and Ryan have reunited once again and are back seeing each other.