He started in films as an agent in 1963. In 1969, Ladd moved to London to produce, making nine films, including The Walking Stick, A Severed Head, Villain, The Nightcomers, and X Y & Zee. He returned to the States in 1973 to become Head of Creative Affairs at 20th Century Fox.

He came to Fox President Gordon Stulberg to request consideration for making George Lucas' Star Wars. Stulberg approved the production and they remained as Lucas' support at times when the Board of Directors of 20th Century Fox wished to shut down production. The production was plagued by location difficulties, story problems and budgetary disagreements for a project that was mainly considered a pending embarrassment before the studio likely closed its doors. However, when Ladd saw first hand the audience's rapturous appreciation of the film at its first public screening at the Northpoint Theatre in San Francisco in early May 1977, he was moved to tears at seeing the unlikely production he and Stulberg had supported against all odds become a spectacular validation of their efforts.

During three very successful years Ladd was President of Fox. Star Wars and Alien were a few of the classics during his tenure. But in 1979 Ladd left his position to found his own production company, The Ladd Company. He enjoyed great successes with comedies like Night Shift and Police Academy, Oscar Winners The Right Stuff and Best Picture, Chariots of Fire, and Gone Baby Gone that won many Film Critics awards. The company also produced the cult classic Blade Runner.

In 1985, Ladd joined MGM/UA, eventually becoming Chairman and CEO of MGM-Pathé Communications. During his tenure MGM/UA enjoyed hits like A Fish Called Wanda, Moonstruck, and Thelma & Louise. Ladd reformed the Ladd Company with Paramount Pictures in 1993 where he produced the hits The Brady Bunch Movie and Best Picture Winner Braveheart.

Ladd received the 2,348th star on the Hollywood Walk of Fame on Friday, September 28, 2007.