The announcement confirmed what already seemed to be a foregone conclusion after Mayfield replaced an injured Tyrod Taylor last Thursday against the New York Jets and led the Browns (1-1-1) to a come-from-behind win -- the team's first in 635 days.
Mayfield made his NFL debut on Thursday when he relieved Taylor, who sustained a concussion. The rookie rallied the Browns from a 14-point deficit to beat the Jets 21-17 in front of a frenzied home crowd at FirstEnergy Stadium. He completed 17 of 23 passes for 201 yards in a little over one half of work.
Mayfield was the No. 1 overall pick in the 2018 NFL Draft after winning the Heisman Trophy last season at Oklahoma.
"Baker understands there's still a lot of work to do," Jackson said. "Now the other added pressure of being out there first is there. But I think he can handle it. He's demonstrated that."