After this year's 1,000-yard, 11-touchdown season, Harris will reportedly return for one more fall in Tuscaloosa.
Ridley made his announcement less than 48 hours after the Crimson Tide beat Georgia in the College Football Playoff National Championship Game Presented by AT&T.
"In announcing my entrance into the upcoming 2018 NFL Draft, I know that thoes who come after me will take this program to even greater heights", Ridley wrote. The 6-foot-1, 190-pounder is second in school history with 220 career catches and third with 2,749 yards.
CBSSports.com had Harris ranked as the 35th best prospect in the NFL Draft - a projection just outside of the first round - and as the fifth-best running back. "The future of this program is indeed in great hands".
This season, Ridley finished the year with 63 receptions for 967 yards and five touchdowns.
No player boosted his stock at the end of the season more than Payne, who earned defensive MVP honors in both the national title game as well as the Alabama's semifinal win over Clemson.