At one time a literary agent who represented such writers and directors as John Badham, Paul Brickman, Alvin Sargent and David Seltzer, Rosenberg joined Warner Bros. as a vice president in the studio's production division in 1978. Five years later he became president of production worldwide, developing and overseeing "The World According to Garp", "Never Say Never Again (both 1983), "The Killing Fields" and "Greystoke: The Legend of Tarzan, Lord of the Apes" (both 1984). Rosenberg left Warner Bros. after seven years and soon thereafter partnered with Sydney Pollack at Mirage Enterprises, a company the director-producer had formed to help manage such films as "Absence of Malice" (1981), "Tootsie" (1982) and "Out of Africa" (1985). With Rosenberg's help, Pollack expanded Mirage's slate to producing "The Fabulous Baker Boys", "Major League" (both 1989), "Presumed Innocent" (1990) and "King Ralph" (1991).
By the time the last of these films had reached audiences, however, Rosenberg and Pollack had parted company, with Rosenberg forming Spring Creek Productions with his wife, producer Paula Weinstein. In 1990 the duo signed a production agreement with Rosenberg's alma mater, Warners, on the studio's lot at Burbank. Rosenberg and Weinstein successfully helmed the HBO telefilm "Citizen Cohn" (1992), based on the life of shark attorney Ray Cohn, who began his career as assistant to Wisconsin senator Joe McCarthy during the 1950s. Spring Creek was filming "Flesh and Bone" and "Fearless" for Warners when Rosenberg was stricken by a heart attack at age 44.