The surprising re-signing is expected to come later this month, according to ESPN's Adam Schefter ... with the dollar amount a staggering figure considering Cam's up-and-down 2020 season.

Newton joined the Pats last summer on a 1-year contract -- his base salary was just $1 million with millions in incentives, but unclear how much he ultimately pocketed from the deal.

And, despite a good opening stretch of games, the 31-year-old finished the season with just 8 TD passes and 10 interceptions.

The year was so rocky for Newton -- who battled a mid-season bout with COVID and ultimately went 7-8 as the team's starter -- most thought the Patriots would move on this offseason.

Clearly, though, the Pats saw enough from Cam to want him back ... and the big money suggests he'll be their starter in 2021.

Of course, the news has to be music to Newton's ears ... the former MVP has spoken VERY highly of his time in New England.

In fact, Cam recently called Bill Belichick "misunderstood" and "dope as s***" on a recent edition of the "I AM ATHLETE" podcast.

By the way, if you're wondering what kind of shape Cam is in this offseason ... it's pretty good -- check out the dude's moves at a roller rink in Atlanta last month.