Derek married Turkish-born prima ballerina Pati Behrs Eristoff in 1948.
They had a son, Russell Andre (1950–1999), who was paralyzed from the chest down due to a 1969 motorcycle accident, and a daughter, Sean Catherine (born 1953), who later wrote a memoir titled Cast of Characters, published in 1982, about their dysfunctional relationship.
Derek walked out on his wife and family in late summer 1955 after meeting 19-year-old aspiring Swiss actress Ursula Andress, who spoke almost no English when they met.
He and Behrs were divorced in 1956.

In 1957, Derek married Andress in a quickie Las Vegas ceremony.
Five years later, her small role in the James Bond film Dr. No launched her career.
Derek threw Andress out of his California home in 1964 over rumors that she had been seeing actor Ron Ely.
Andress then went back to Europe, engaging in public affairs with co-stars John Richardson and Marcello Mastroianni before officially leaving Derek for Jean-Paul Belmondo in 1965.
The pair divorced in 1966.

In September 1965, Derek became involved with American actress Linda Evans, at the time starring in television's The Big Valley.
A couple of years into their relationship, Evans reduced her appearances on the show to spend more time with him, and financed his alimony and child support payments to Behrs, as he had quit acting by then to pursue photography and directing.
 They eloped in Mexico in 1968, with Sean as a witness.

In 1973 Derek, Evans and 16-year-old high school dropout Mary Cathleen Collins traveled to the Greek island of Mykonos to make the film And Once Upon a Time (unreleased until 1981, under the title Fantasies).
During filming, Derek and Collins began an affair.
Evans returned to the United States and filed for divorce in 1974, but Derek and Collins stayed in Europe until she turned 18 in November of that year, in order that he would avoid statutory rape charges.

Collins became known to the public as Bo Derek following their marriage on June 10, 1976, and achieved international fame in 1979 with her role in the Blake Edwards film 10.
The couple remained together until John died in 1998.

Derek suffered a heart attack in 1986, but completely recovered.

Derek had one granddaughter, Alyce Derek (born 1969) from Russell's marriage to Lynette Berry.
He became a great-grandfather in 1996.

In 2019, Derek's great-granddaughter Asia Duran was arrested on drug charges in Santa Maria.
Derek married Turkish-born prima ballerina Pati Behrs Eristoff in 1948. They had a son, Russell Andre (1950–1999), who was paralyzed from the chest down due to a 1969 motorcycle accident, and a daughter, Sean Catherine (born 1953), who later wrote a memoir titled Cast of Characters, published in 1982, about their dysfunctional relationship. Derek walked out on his wife and family in late summer 1955 after meeting 19-year-old aspiring Swiss actress Ursula Andress, who spoke almost no English when they met. He and Behrs were divorced in 1956.
In 1957, Derek married Andress in a quickie Las Vegas ceremony. Five years later, her small role in the James Bond film Dr. No launched her career. Derek threw Andress out of his California home in 1964 over rumors that she had been seeing actor Ron Ely. Andress then went back to Europe, engaging in public affairs with co-stars John Richardson and Marcello Mastroianni before officially leaving Derek for Jean-Paul Belmondo in 1965. The pair divorced in 1966.
In September 1965, Derek became involved with American actress Linda Evans, at the time starring in television's The Big Valley. A couple of years into their relationship, Evans reduced her appearances on the show to spend more time with him, and financed his alimony and child support payments to Behrs, as he had quit acting by then to pursue photography and directing.  They eloped in Mexico in 1968, with Sean as a witness.
In 1973 Derek, Evans and 16-year-old high school dropout Mary Cathleen Collins traveled to the Greek island of Mykonos to make the film And Once Upon a Time (unreleased until 1981, under the title Fantasies). During filming, Derek and Collins began an affair. Evans returned to the United States and filed for divorce in 1974, but Derek and Collins stayed in Europe until she turned 18 in November of that year, in order that he would avoid statutory rape charges.
Collins became known to the public as Bo Derek following their marriage on June 10, 1976, and achieved international fame in 1979 with her role in the Blake Edwards film 10. The couple remained together until John died in 1998.
Derek suffered a heart attack in 1986, but completely recovered.
Derek had one granddaughter, Alyce Derek (born 1969) from Russell's marriage to Lynette Berry. He became a great-grandfather in 1996.
In 2019, Derek's great-granddaughter Asia Duran was arrested on drug charges in Santa Maria.
John Derek