The two had been vying for the job for most of the off-season before Browns coach Mike Pettine and his staff opted for Hoyer, mainly because of his previous experience in the National Football League (NFL) and his leadership qualities.
"He was the clear leader from the beginning," Pettine, who consulted with offensive coordinator Kyle Shanahan and quarterbacks coach Dowell Loggains before reaching a decision, said in a statement.
"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."
The Browns will launch their NFL regular season on Sept. 7 in Pittsburgh against the Steelers.
Though Hoyer completed only two of six passes for 16 yards in Monday's preseason 24-23 loss to the Washington Redskins, Pettine said that he had considered Hoyer's entire "body of work" before a final decision was taken.
"I think Brian's been very poised," Pettine said of Hoyer, who has battled back from a season-ending injury he suffered against the Buffalo Bills last October. "I think he's handled the situation well. He's had a lot of things going on."
Hoyer, who has started four games in his NFL career since being signed as an undrafted free agent by the Patriots in 2009, went 3-0 as a starter for Cleveland last season.
Manziel, nicknamed "Johnny Football" in college, found instant popularity since being drafted in the first round by the Browns, but his bid for the starting quarterback job was not helped by his offseason behavior.
Criticized by many for his love of partying before training camp, he also played poorly in Monday's defeat in Washington and lost his composure in the third quarter by making an obscene gesture toward the Redskins bench.
However, Pettine said the decision to start Hoyer did not reflect poorly on Manziel, whose No. 2 jersey became the National Football League's top seller last month.
"He's certainly made great strides," Pettine said. "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."
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Gene Cherry)