The show originated from a script called Double Twist, written by novelist Sidney Sheldon in the early 1970s for CBS about a married couple who were spies, which remained unfilmed for years.

Producers Aaron Spelling and Leonard Goldberg later revived the idea and gave the script to screenwriter Tom Mankiewicz, who had written three James Bond films, to update it for a contemporary weekly series; he renamed it Hart to Hart and made his directorial debut on the pilot episode.

Cary Grant was the producers' initial choice to play Jonathan Hart, but at 75 and retired from acting since 1966, he was passed over in favor of a younger actor, Robert Wagner.

George Hamilton was also considered for Jonathan Hart, but Aaron Spelling rejected him, reasoning that audiences would resent Hamilton for being that rich, whereas no one would begrudge Robert Wagner the role.

ABC wanted Robert Wagner's then-wife Natalie Wood to co-star as Jennifer Hart, but Wagner opposed the idea; Wood instead made a cameo in the pilot as an actress playing Scarlett O'Hara.

Suzanne Pleshette, Kate Jackson, and Lindsay Wagner were considered for the role of Jennifer Hart before Robert Wagner suggested Stefanie Powers, with whom he had previously worked on an episode of It Takes a Thief.

Robert Wagner wanted boxer Sugar Ray Robinson to play the majordomo Max, but ABC executives were uneasy about casting a Black man as a servant to a wealthy white couple, so Lionel Stander was cast instead; Stander had also played a character named Max alongside Wagner in It Takes a Thief and in Mankiewicz's 1976 film The Cassandra Crossing, in which the leads were likewise named Jonathan and Jennifer.

The Harts' ranch-style exterior house previously belonged to Dick Powell and June Allyson, old friends of Wagner and Spelling; the real estate, called Amber Hills, sits on 48 acres in Mandeville Canyon, Brentwood, and its real address of 3100 Mandeville Canyon Road was fictionalized as 3100 Willow Pond Road, Bel Air in the show.

In 2013, Adult Swim's The Greatest Event in Television History aired a shot-for-shot remake of the Hart to Hart opening sequence, hosted by Jeff Probst, starring Adam Scott and Amy Poehler as the Harts and Horatio Sanz as Max.