Also named as recipients of the Altman honor were the film's casting director Laura Rosenthal and ensemble cast members Christian Bale, Cate Blanchett, Marcus Carl Franklin, Charlotte Gainsbourg, Richard Gere, Bruce Greenwood, Ben Whishaw and Ledger.
Blanchett, Franklin and Greenwood looked solemn as they stood behind Haynes while the filmmaker gave his acceptance speech.
"Honoring this amazing ensemble today is so bittersweet given how shattered all of us are by Heath's inconceivable absence," Haynes said. "We all loved him so dearly. He really was unlike anybody I'd ever known."
Noting how the actor was also the "creator of some of the most exquisite and most diverse music videos I'd ever seen," Haynes revealed Ledger had "just started circulating a feature script he was planning to direct" based on Walter Tevis' book "The Queen's Gambit" before he died.
"I have no doubt he'd have made an astounding director," Haynes said.