Penned a host of scripts during the 1950s and 60s, many of them so-called "women's pictures", but is best remembered for his work on several witty Hitchcock films. Twice nominated for an Oscar ("Rear Window" 1954, "Peyton Place" 1957), Hayes had a string of respectable box office and occasional critical hits. His other Hitchcock collaborations include, "The Trouble With Harry" (1955), "To Catch a Thief" (1955) and the remake of "The Man Who Knew Too Much" (1956). His relationship with Hitch soured when the trades began referring to their projects as "Hitchcock-Hayes" films. Hitchcock was never crazy about sharing credit with anyone. In 1956 he asked Hayes to work for nothing on a film he owed Warner Bros., "The Wrong Man". When Hayes refused Hitchcock never spoke to him again.

Hayes scripted such steamy outings as the garish Joan Crawford vehicle "Torch Song" (1953) and the Susan Hayward-Bette Davis sudser "Where Love has Gone" (1964). He also adapted several bestsellers for the screen that featured other legendary above-the-title Hollywood ladies: Lana Turner ("Peyton Place" 1957), Elizabeth Taylor ("Butterfield 8" 1960; for which she won her first Oscar), Carroll Baker ("The Carpetbaggers") and Deborah Kerr ("The Chalk Garden" both 1964), as well as stage plays, "The Matchmaker" (1958) and "The Children's Hour" (1961). After the disastrous Sophia Loren war drama "Judith" (1966), he was absent for fourteen years from theatrical features (1966-80), during which time he wrote TV-movies "Winter Kill" (1974) and "Nevada Smith" (1975), based on the 1966 Steve McQueen of the same title, which is an adaptation of "The Carpetbaggers". He returned to the big screen with the erotic feature "Champagne for Breakfast" (1980).

When his wife was diagnosed with ovarian cancer, Hayes returned to his native New England where he taught screenwriting at Dartmouth College. In 1994, he sold the script for "Iron Will", the story of a boy who earns his medical school tuition by training an odd bunch of mutts and entering them in a dogsled race, to Disney.