Mr Melcher died on Fridat at the age of 62 after a long battle with cancer, Doris Day’s spokeswoman Linda Dozoretz said.
During the musical career that he launched in 1964, Mr Melcher worked with famed groups including The Beach Boys, The Byrds, The Mamas and the Papas, Paul Revere and the Raiders, The Turtles, Glen Campbell and Randy Newman.
But Mr Melcher’s name will forever be linked to the terrifying events of August 1969 when Charles Manson and his gang of disciples murdered movie star Sharon Tate and four other people at Mr Melcher’s former home.
Mr Melcher had been given a demo tape by aspiring musician Manson but turned down his request for a recording contract.
Mr Melcher occupied the house with his girlfriend Candice Bergen until shortly before the murders took place.
In August 1969, Manson, who had visited Mr Melcher at his home and was familiar with its layout, dispatched his cult followers to the mansion on a bloody murder spree.
The Manson “family” members brutally killed the eight-month pregnant Tate, the wife of film director Roman Polanski and four other people on the property, sending shudders of terror through Hollywood.
Ms Dozoretz said in her statement announcing Melcher’s death that he had not been the intended target of the killers.
“Melcher had moved to Malibu several months earlier and police were able to establish that Manson knew of Melcher’s new address, as it was one of many homes Manson and his followers vandalised,” she said.
Mr Melcher sang background vocals and co-wrote The Beach Boys’ song “Kokomo,” for which he was nominated for a Golden Globe award for the 1988 film “Cocktail,” starring Tom Cruise.
Mr Melcher also served as an executive producer for “The Doris Day Show” television series from 1968-1972, and created and co-produced Doris Day’s return to television in the mid-1980s in “Doris Day’s Best Friends.”
He also helped run his animal rights activist mother’s non-profit organizations, the Doris Day Animal League and the Doris Day Animal Foundation.
Mr Melcher is survived by his 80-year-old mother, who lives in the northern Californian town of Carmel, his wife, Terese and his son, Ryan.