Terms of the endorsement deal were not disclosed.
The idea actually started with Golden State Warriors power forward Draymond Green.
"He just texted me one day and said, 'You should do a deal with Mack,'" Mack said.
Mack hadn't thought of it before, but the truck company wasn't foreign to him.
"Whenever we were on the road when I was younger, I remember my father pointing out the trucks that had Mack on them," Mack said.
So Mack called his agent Joel Segal, president of team sports for sports agency Lagardere, and asked him to make the connection.
"It was really a cold call," Segal said. "But it couldn't have gone better."
It helped that the folks at Mack had talked about the defensive end in the past.
"Obviously we share the same name, but what really drew us to him, based on what we had heard, was that we seemed to share the same fundamentally American values of hard work, family, honesty and humility," said John Walsh, Mack's vice president of global marketing and brand management.
While heavy-duty Mack trucks aren't sold in dealerships to fans, and the company has traditionally marketed specifically in the trucking trade media, Walsh said using Khalil can have an impact.
"In recent years, in line with the changing technology landscape, we've increased our focus on digital, including social media, to build brand awareness and affinity and connect with both existing and potential customers," he said. "We believe that working with Khalil will also help us reach a younger demographic, which is key to the future success of Mack and the trucking industry in general."
Mack, who is among the NFL's top defensive players, counts Nike and New Era among his other endorsements.
Mack's deal is the third one this year with an NFL player that was a result, at least in part, of his name. Dallas Cowboys draft pick Taco Charlton, also a Segal client, signed a endorsement deal with a restaurant chain called Taco Bueno. Denver Broncos draft pick Jake Butt, a tight end, signed a draft-day deal with Charmin toilet paper.