Leonardo DiCaprio and Scarlett Johansson have paid heartfelt tributes to Robert Redford.

On Tuesday, a representative for the actor-director announced that he had died in his sleep at his home in Sundance, Utah. Redford was 89.

Following the sad news, DiCaprio took to Instagram to post a black-and-white photo of the Butch Cassidy and the Sundance Kid star.

In the accompanying caption, the actor emphasised Redford's contributions to cinema and environmental causes.

"Actor, activist, passionate environmentalist, and champion of the arts," he wrote. "His unwavering commitment to protecting our planet and inspiring change matched his immense talent. His impact will endure for generations to come."

While in a statement to People, Johansson reflected on working with Redford on the 1998 film The Horse Whisperer - her first major acting role.

"Bob taught me what acting could be, and it was from his generosity and patience that I was inspired to pursue the possibilities of the craft," she commented. "Bob, thank you for your belief in me and for your grace and guidance. You inspired so many artists, me included, to go deeper, to stay present, to push creative boundaries, and to explore further, and for that, we are forever grateful."

Elsewhere, Cynthia Nixon credited Redford for "almost singlehandedly" ushering in "the golden age of independent film" when he founded the Sundance Film Festival and Sundance Institute in the late '70s.

"Such a visionary. Such a loss," the actress posted on Instagram.

In addition, Julianne Moore noted Redford was the "first movie star I ever loved" and Rob Lowe insisted the actor's "body of work will never be matched".

Josh Brolin recalled how the Ordinary People filmmaker always "beat to his own drum", while Kerry Washington described the Hollywood legend as a "generous and kind soul".

Redford is survived by his wife Sibylle Szaggars, two daughters, and seven grandchildren.