Walker chose to attend Michigan State University to pursue a degree in Supply Chain Management rather than accepting the Cincinnati Reds offer after getting drafted out of high school. As a freshman, Walker finished top three in batting average (.285), hits (51), doubles (11), RBI (19), and runs scored (23). Walker hit .415 batting average, with 30 RBI and 12 doubles, while swiping 14 stolen bases as a junior in high school leading to an All-State, First-Team All-Area and All-Conference selection. He followed this stellar performance up by hitting .432 with 12 home runs, 11 doubles and 49 RBI on his way to a .968 slugging percentage as a senior. This outstanding season led to a No. 2 overall ranking in the state of Illinois and 180th nationally by Perfect Game.