After agreeing to a two-year deal with Walker, the Panthers traded Kyle Allen to the Washington Redskins for a fifth-round pick, sources told ESPN. Allen started 12 games last season after Cam Newton was sidelined with a foot injury.
Walker deal is worth $1.565 million and includes a $150,000 signing bonus and a $25,000 workout bonus next year, a source told ESPN's Dianna Russini.
Monday's moves came almost a week after Carolina reached terms on a three-year, $63 million contract with former New Orleans quarterback Teddy Bridgewater. He will replace Newton, who will be released if a trade can't be worked out before Bridgewater passes his physical to complete his deal, according to a league source.
Walker will compete with 2019 third-round pick Will Grier for the backup spot.
For Walker, this is a reunion with the Panthers' new coach, Matt Rhule. The two were a part of the rebuilding process at Temple from 2013 to 2016.
"I've been through it with him," Walker told ESPN.com about his experience with Rhule. "I know it does work. I know it takes time. You've just got to trust in what he's saying and believe in what he believes, and eventually it will turn."
Rhule calls that his "process," and Walker's understanding of the process played a part in Carolina's decision to sign him.
"This process is going to be a daily tough grind," Walker said. "You have to get after it. It's going to be a lot of business. Rhule is a business guy who likes to make sure everything gets done the right way. We're going to push each other to get the best out of each player."
While Rhule ran more of a power running game at Temple, Walker expects a more wide-open, spread offense at Carolina, similar to what Rhule ran at Baylor and new offensive coordinator Joe Brady ran at LSU.
"I'm extremely excited," Walker said. "I've been seeing the Saints' offense and LSU's high, dynamic offense, as well. It's going to give us the ball to spread the ball around and do a lot of great things."
Walker became available to sign with an NFL team Monday, three days after the XFL announced its inaugural season had been canceled because of the coronavirus pandemic.
The 5-foot-11 Walker was one of the XFL's top players and led the Houston Roughnecks to a 5-0 record. He led the league in passing yards (1,338 yards) and touchdown passes (15).
After the league shut down, Walker returned to his New Jersey home. He has been working out in his apartment complex's gym while practicing social distancing.
"My mood is definitely frustrated by that," Walker said. "It's difficult. I want to be out there picking up the new offense and be around my new teammates to see what we've got."
But having an understanding for Rhule puts him ahead of most on the Panthers, who've never had a chance to be on the field with their new coach.
"He just wants me to come in here and compete," said Walker, who was keeping in touch with Rhule before the coronavirus shut things down. "He believes in me. He wants to be a leader and factor in building the team."
Walker joins a Carolina team in the midst of a transition of the roster, not just quarterback. The Panthers already have moved on from most of the older veterans. The first nine free agents they reached deals with were 27 or younger, and all signed one- to three-year deals.
Walker, 25, was one of the best players in Temple history and led the Owls to back-to-back 10-win seasons in 2015 and 2016. He is the school's all-time leader in virtually every passing statistic, including yards (10,668), touchdowns (74) and completions (830).
Temple went 28-19 in games started by Walker, who was the starting quarterback for all 28 of Rhule's wins at the school.
Walker doesn't know when he will join Rhule and his new teammates in Charlotte. He plans to spend time with family and work out as safely as possible to stay in shape.
"I'm just taking it one step at a time," he said. "Hopefully, I get a chance to compete for a backup job and, once I get there, push the guys and hopefully things open up."