The Cards selected Rosen with the No. 10 overall pick in the 2018 NFL draft.
The UCLA product is part of a crowded quarterback depth chart with veterans Sam Bradford and Mike Glennon, but he will potentially have a chance to earn the starting job as a rookie.
Rosen is already among the biggest names to represent Adidas in the NFL, joining Green Bay Packers quarterback Aaron Rodgers, Denver Broncos linebacker Von Miller, Houston Texans wide receiver DeAndre Hopkins, Packers tight end Jimmy Graham and Dallas Cowboys quarterback Dak Prescott.
Rosen said about his deal with Adidas, per Hayes:
"It's still hard to believe. It's something you dream about as a kid growing up playing this game, playing in the NFL, and getting an endorsement from a company you really believe in. I'm ready to play now. The season can't get here quick enough.
"Adidas is serious about the environment, and Parley for the Oceans is something I'm really invested in. I've always said I want to use my position as an NFL football player to affect change off the field. This is a great start. It's really a perfect fit for me because adidas is serious about the environment and making a difference."
While there isn't immediate pressure on Rosen to start in 2018, Cardinals head coach Steve Wilks said in late May that the idea of him starting as a rookie isn't a long shot.
In his final season at UCLA, Rosen completed 62.6 percent of his passes for 3,756 yards, 26 touchdowns and 10 interceptions. He was the fourth quarterback to be selected in this year's draft behind Baker Mayfield, Sam Darnold and Josh Allen, but he has the tools to become the best of the bunch.
In late May, former Arizona radio personality Mike Jurecki reported that an unnamed Cardinals veteran told him, "I think we have something special in Rosen."
The Cards are looking to replace Carson Palmer, who retired this offseason after 14 NFL seasons, including five in Arizona.
The Cardinals seemingly believe Rosen is their long-term answer after making him their 2018 first-round pick, and Adidas expressed confidence that he will thrive when given the opportunity.