Johnson was born in Flat Creek, Missouri. His father was a farmer, his mother a beautician. At the age of 6, he moved from Missouri to Wichita, Kansas. He graduated from South High School in Wichita, Kansas in 1967 and attended the University of Kansas in Lawrence, Kansas. He is of English origin.

In the late 1960s, he was one of the male contestants on the popular television show The Dating Game.

Johnson was married twice to actress Melanie Griffith (briefly in 1976 and then from 1989-1996) and is currently married to Kelley Phleger of San Francisco. They were married in 1998. Ms. Phleger is related to the Gettys of Getty Oil.

Johnson lived with Patti D'Arbanville from 1981 to 1985.

Johnson had a relationship with Barbra Streisand and created a single with her called "Till I Loved You". The single was the theme song to the 1987 film Nuts.

He was briefly engaged to actress Jeanne Anderson in 1996.

Johnson has a son with D'Arbanville, Jesse Johnson, born in December 1982, a daughter with Griffith, Dakota Johnson, born in October 1989, and a daughter with Phleger, Atherton Grace Johnson, born December 28, 1999 and a son, Jasper Breckinridge Johnson, born June 6, 2002. Their third child and second son, Deacon, was born April 29, 2006.

Johnson studied drama at the American Conservatory Theater in San Francisco. His first major role was in the 1969 Los Angeles stage production of Fortune and Men's Eyes in which he played Smitty, the lead role. This exposure led to the quickly forgotten 1970 film The Magic Garden of Stanley Sweetheart. He continued to work on stage, film and television without breaking out into stardom. His notable films from this period were The Harrad Experiment (1973) and A Boy and His Dog (1975). He was referred to as a "six-time loser" in Hollywood as a result of having been featured in six failed pilot television series.

In September 1984 Johnson's fortunes changed when he became a household name as a result of his co-starring role as Sonny Crockett in the popular 1980s cop series, Miami Vice. In this role, Johnson played a police detective working undercover as a drug smuggler. He typically wore thousand dollar Versace and Hugo Boss suits over pastel cotton t-shirts, drove a Ferrari Daytona (later a Ferrari Testarossa) and lived on a 42-foot yacht with his pet alligator Elvis. Miami Vice was noted for its revolutionary use of music, cinematography, and imagery as well as a more glitzy take on the police drama genre.

Don Johnson later starred in the 1996-2001 drama Nash Bridges with Cheech Marin and Yasmine Bleeth. Johnson played the title role of Nash, a detective for the San Francisco Police Department. In Bridges Johnson was again paired with a flashy convertible car, this time an electric yellow 1971 Plymouth Barracuda.

In the fall of 2005, he briefly starred in The WB courtroom television show Just Legal as a jaded lawyer with a very young and idealistic partner (Jay Baruchel); the show was cancelled in October 2005.