Coach Mike Pettine made the announcement on Wednesday, opting for Hoyer over one of the league's most talked-about rookies.
Hoyer has started both the Browns' pre-season games so far and took most of the first-team snaps in the mini camps, and Pettine insisted he was the obvious choice.
"He was the clear leader from the beginning," Pettine said in a statement released by the Browns on Wednesday.
"We've maintained all along that if it was close, I would prefer to go with the more experienced player.
"Brian has done a great job in the meeting rooms and with his team-mates on the practice field and in the locker room."
Hoyer will also start Saturday's pre-season game at home against St Louis, although it was expected that he would be pushed close by NFL's latest poster-boy Manziel for the regular-season job.
The 21-year-old was drafted as the 22nd pick by the Browns in May after a standout college career and has since generated plenty of headlines.
But despite the hype, Pettine feels that he is still learning his trade at elite level.
"He's certainly made great strides," Pettine said of Manziel.
"We are pleased with where he is, and he has shown that he has come a long way in his ability to pick up the playbook, be coachable and lead an offense.
"We are confident that Johnny is going to have a great future, but we just felt that Brian still had a decided edge on him."