The controversial 22-year-old spent more than two months in rehab during the offseason and is currently under NFL investigation to determine whether or not he violated the league's personal conduct policy due to a recent alleged domestic dispute.
However, after impressing during the 30-9 loss to the Pittsburgh Steelers while deputising for injured veteran Josh McCown, coach Mike Pettine has decided to promote Manziel in the pecking order.
“He showed significant progress," Pettine said on Monday. "That was one of the better quarterback performances.
“I've seen where things have gone bad early and guys go in the tank and they get that glazed look in their eye. He was the exact opposite. He was loose. He was into it.
“I thought he did an outstanding job in between series, getting input from the quarterbacks.
"I just thought the improvement he made from the Cincinnati game to this one was a leap. Kind of given what he's gone through, you're just proud of the kid and happy for him."
Defeat to Pittsburgh left the Browns 2-8 for the season and 2-13 in their last 15 games under Pettine, fuelling speculation that he could be the next NFL coach to lose his job.
He insists that is not playing on his mind, though he acknowledges that as long as results don’t improve the rumours won’t subside.
"If you start coaching to save your job, then you are not doing your job,” he said.
“I am passionate about my job. I love it here in Cleveland. I love the guys in the locker room and on the staff.
"There is nothing that I want more for this team and for this city than to be successful. While I am still sitting in this chair, I am going to do everything I can to make that possible.
"We are in an age of instant gratification and win now. You could be headed in the right direction in a lot of different phases of the program, but when you are not winning, that is what we are all ultimately judged on.
“This is a pass/fail league. We have failed a heck of a lot more times than we have passed, and that is the bottom line."