Lynn made the announcement during his Wednesday news conference.
Taylor and 2020 No. 6 pick Justin Herbert were competing for the starting job, though Lynn made no secret throughout the offseason that he expected to go with the veteran to open the regular season.
Lynn told Sports Illustrated's Albert Breer in April that "Taylor's going to be starting it off" in camp:
"He's earned that right. His teammates respect the hell out of him, he's a leader on this football team. Our young quarterback's gonna learn a lot from Tyrod Taylor. Tyrod Taylor's one of the most respected players on our team, and he doesn't say a whole lot either. ...
"[But] it's a competition, bro. There's a competition at every position, not just this one. I can't just say Tyrod's gonna be the starting quarterback for the whole year if this young man goes in there and wins the job."
Week 1 will mark Taylor's first start since Sept. 20, 2018, when he played for the Cleveland Browns. The 31-year-old threw six passes in eight games as Philip Rivers' backup last year.
Taylor owns a 23-21-1 career record and led the Buffalo Bills to the playoffs in 2017.
The Chargers will open the regular season Sept. 13 against the Cincinnati Bengals at Paul Brown Stadium.