In the 1970s, Heard frequently appeared on the stage, television, and films. He appeared off-Broadway in 1974 in Mark Medoff's play The Wager and at the Eugene O'Neill Theater Center in 1977 in a series of plays. In 1979 he played Arthur Dimmesdale in a television production The Scarlet Letter. Heard won Obie Awards for his performances in Othello and Split in 1979–80. He was the male lead in the 1979 film Head Over Heels.
John Heard reached the age of 70 in 2016. He has an American nationality and he belongs to the white ethnicity. Heard was married for six days to actress Margot Kidder in 1979. He has a son, John Matthew "Jack" Heard, with ex-girlfriend Melissa Leo. He has two other former wives, Sharon Heard and Lana Pritchard. Sharon and Heard have two children together, son Max and a daughter named Annika. Heard and Pritchard married on May 24, 2010, in Los Angeles and divorce on December 22nd, 2010 after nearly 7 months of marriage.
In 1981, he had the starring role of Alex Cutter in the film Cutter's Way. He played the lover of Nastassja Kinski, one of the main characters, in the remake of Cat People. In 1984, he co-starred as photographer George Cooper in C.H.U.D. (Cannibalistic Humanoid Underground Dwellers) alongside future Home Alone co-star Daniel Stern. The net worth of U.S. $ 2.5 million. His major part of earning comes from his acting.