Ledger was posthumously given the Australian Film Institute's international award for best actor for his role as the Joker in "The Dark Knight."
His father, Kim; mother, Sally; and sister Kate accepted the award.
"It's been without a doubt the most difficult year, losing such a loved family member," said Kate Ledger, fighting back tears.
"We are so proud of him and humbly accept this award on behalf of his beautiful daughter, who we will cherish forever," she said, referring to Matilda, his 3-year-old daughter with actress Michelle Williams.
Ledger's performance in the Batman blockbuster is regarded as having a solid chance for a posthumous Academy Award for best supporting actor.
"It was this swaggering, psychopathic clown that turned his career into a legacy and the name Heath Ledger into an ongoing inspiration to actors everywhere," the Australia Film Institute said at the awards ceremony Saturday night in Melbourne.
Sally Ledger thanked the film institute for the tribute to her son, who died of an accidental prescription drug overdose in New York in January. He was 28.
"We are immensely proud of him, not only for his professional achievements, but in the way he truly cherished his family, friends and his precious Matilda," she said.
"Heath was never one to accept mediocrity, he put his heart and soul into achieving what he believed was required and followed his passions with great enthusiasm and an insatiable curiosity," she added.