Blanchett's comments came moments after Brendan Fraser gave a highly emotional, choking speech in which he thanked voters for his best actor prize for "The Whale."
Fraser, a major Hollywood star in the late 1990s and early 2000s with hits such as "The Mummy," had endured a long fallow period before his performance as a morbidly obese teacher in his new drama drew widespread acclaim.
"I was in the wilderness. And I probably should have left a trail of breadcrumbs. But you found me," Fraser told director Darren Aronofsky.
"If you -- like a guy like Charlie who I played in this movie -- in any way struggle with obesity, or you just feel like you're in a dark sea, I want you to know that if you too can have the strength to just get to your feet and go to the light, good things will happen," Fraser said to a standing ovation.
The Critics Choice Awards are one of a raft of major award shows in the build up to the Oscars, which take place this year on March 12.
Surreal sci-fi "Everything Everywhere All at Once" won best picture at Sunday's high-profile critics awards, boosting its hopes for the top Academy Award prize.