According to Lee's death certificate, the 95-year-old comic book icon's primary causes of death was heart and respiratory failure.
He also suffered from aspiration pneumonia, a condition in which a patient inhales stomach acid, saliva or food into their lungs.
Lee passed away on Nov. 12 at 9:17 a.m. PT at Cedars-Sinai Medical Center in Los Angeles.
The death certificate notes that Lee's remains were cremated and given to his daughter, J.C. Lee.
A small, private funeral was held for the Spider-Man co-creator earlier this month in accordance with his wishes.
Lee suffered from several medical issues leading up to his death, including pneumonia, an irregular heartbeat and vision issues.
His wife of nearly 70 years, Joan, passed away in 2017 at age 93.
In a video released posthumously, Lee expressed mutual admiration for his fans.
"There’s something if you think about it, that is wonderful about somebody caring about you, as I care about them, whom you’ve never met, who may live in another part of the world," he said. "But they care, you have something in common and occasionally you contact each other. This business of fans, I think is terrific. And I love 'em all."
EDITOR’S NOTE: A previous version of this report gave an incorrect name for Stan Lee’s late wife. Her name was Joan, not Jane.