Scout's No. 9 rated guard, Walker said his relationship with recruiting coordinator Ed Orgeron and the opportunity for immediate playing time were enough to secure his commitment over the home state Buckeyes.
"USC has a great coaching staff and it's a nice place," Walker said. "The school is great itself. I'm surrounded by a group of good people.
The Trojans also benefited from Walker's recent official visit, which coincided with his 18th birthday.
"That night we had a little kick back, a little party for my birthday," Walker said. "We had a great time. L.A. is great man. The coaches showed me a lot of love."
The 6-foot-6, 355-pound Walker could be in the mix for start as a freshman, as the Trojans must replace three linemen next season, including right tackle Tyron Smith.
Smith declared for the NFL in December and is expected to be a first-round pick, while another starter, left guard Michael Reardon, decided to pass on his final season of eligibility after graduating and securing a job with his father's construction company.