The 44-year-old was best known for playing Samuel "Screech" Powers in the popular 1990s US sitcom about a group of high school friends and their headmaster.
He had recently completed a first round of chemotherapy after being diagnosed with lung cancer last month.
His condition had deteriorated fast in the last week, said agent Roger Paul.
"Dustin did not suffer. He did not have to lie submerged in pain. For that, we are grateful," he said on Monday.
Saved by the Bell ran for four seasons from 1989 to 1993 and was a global hit series.