Players reported on Wednesday and begin practicing on Thursday. Mayfield won't miss a beat.
The contract includes a signing bonus worth $21,849,440 million, and a fifth-year club option. The fully guaranteed amount is $32,682,980. It includes offset language, which enables the Browns to subtract the amount of a new contract from this guaranteed deal if he signs elsewhere before it expires.
Mayfield and his family were eager for him to get into camp and not miss any practice time, so they urged agent Tom Mills to accept the offset language, a source told cleveland.com.
In exchange, the Browns improved some of the language in the deal.
Offset language might seem insignificant, but the last time the Browns drafted a quarterback in the first round, Johnny Manziel, they cut him after two seasons. In fact, their last three first-round QBs since 1999 were cut before their rookie deals expired. Of course they're not expecting that in this case.
The reigning Heisman Trophy winner was one of five remaining unsigned first-round picks. One of the others is Browns No. 4 overall pick Denzel Ward. Offset language is believed to be the sticking point there too.
The other three are Jets quarterback Sam Darnold (No. 3), Bills quarterback Josh Allen (No. 7) and Bears linebacker Roquan Smith (No. 8).
Mayfield returns to Berea after an eventful summer break that included getting engaged to Emily Wilkinson, a trip to Hawaii, working out with teammates at USC, and winning an ESPY for the nation's best college athlete.
Promoted to second-team offense during the final week of organized team activities in May, Mayfield will try to win the starting job even though Hue Jackson has told him it's Tyrod Taylor's.
"I'm always competitive,'' Mayfield said during rookie camp. "It wouldn't matter what (Jackson) was saying in regards to the competition. I'm still going to compete and try and win that job. So I'm going to listen to him, but I've got to go compete, and first and foremost, I've got to go learn my job.''
Jackson set the tone right from the start, announcing on draft day that Taylor was his starting quarterback and that he wouldn't hold an open competition in camp. He is committed to a proven veteran after 1-31.
"I'm not going to back off of this," he said during rookie minicamp. "We can keep writing this narrative. Tyrod Taylor's the starting quarterback of this football team, and that won't change."
That Taylor and Mayfield worked out together at USC before camp is a good sign. Mayfield heads in striking the right balance between competing and knowing his place.
"It's not about individuals,'' Mayfield said in May. "They brought him and I in because we're both team-oriented guys. He's the starter, and all I can do is help us out. So when you get a guy like that that helps out a locker room in just the best way possible, he's a grinder. He comes in early. He's the last one to leave, and I can only aspire to be like that.''
During minicamp last month, offensive coordinator Todd Haley echoed Jackson's sentiments that Mayfield isn't ready to supplant Taylor anytime soon.
"He has a long way to go,'' Haley said. "I'd say it's clear that Tyrod is the leader of this team.
"Anytime that you're a young player coming into this league, especially a quarterback, it's going to take time. You have a lot of different things that you're dealing with at that position. For him, a guy that has been in the [shot]gun 99 percent of the time, in this division you have to be under center some.
"Whether it's running or play action, those are some of the things that he has really had to work hard at. But I'm happy that we have training camp because young quarterbacks need all of the time they can get."
Now that he's signed and in on time, Mayfield won't miss a minute.