The Texas standout won the Maxwell Award as the best all-around player, beating out Michael Bishop of Kansas State and Cade McNown of UCLA in voting by the Football Writers Association.
Williams also won the Doak Walker Award as the outstanding running back for the second straight year. Michael Cloud of Boston College and Ron Dayne of Wisconsin were the other finalists.
Winning the award was emotional for Williams, who first met Walker at last year's awards show. The two had dinner and Walker made a prophetic statement to Williams: win the award twice.
"From that point on, I made it my job to go out there and win this award again," Williams said. "I was sitting there and I was thinking about last year. It was kind of weird because last year it was just me and Doak and the people he brought with him to dinner and we were all just sitting there talking. Nobody knew who I was because our team wasn't that good. This year, I was getting all the attention and Doak isn't with us anymore. It's weird how things change so much in a year."
Walker died earlier this year from complications arising from a skiing accident in Colorado.
Williams became major college football's career rushing leader with 6,279 yards, breaking Tony Dorsett's mark by 197. He ran for 2,124 yards and 27 touchdowns this season.
Earlier this week, he won The Associated Press' first College Player of the Year Award.
In other awards, Texas A&M lineman Dat Nguyen, the Aggies' career leading tackler with 517, won the Chuck Bednarik Trophy as the defensive player of the year, beating out Andy Katzenmoyer of Ohio State and Jevon Kearse of Florida.
Bishop, who led Kansas State to an 11-1 mark, won the Davey O'Brien National Quarterback Award over Tim Couch of Kentucky and McNown. Bishop ran for 748 yards and 14 touchdowns, and passed for 2,844 yards and 23 TDs.
Bishop was proud to serve as an example to all players who make it to Division I from the junior college ranks.
"It's hard going from high school to juco," Bishop said. "You dream about going straight to Division I. Hard work pays off. Don't go the juco route and have a blowoff year. Go there and work hard and go all out in the classroom and you'll succeed."
Other winners included UCLA interior lineman Kris Farris, Outland Trophy; Louisiana Tech wide receiver Troy Edwards, Biletnikoff Award; Northwestern's Matt Hartl, Sports Spirit Award; Georgia's Matt Stinchcomb, Princeton's Alex Sierk, Mesa State's Josh Penry, and Western Maryland's Tom Lapato, scholar athletes of the year; Florida State kicker Sebastian Janikowski, Groza Award; and Tennessee's Phillip Fulmer, the Eddie Robinson Coach of the Year.
Edwards earned a spot in the college record book with 405 receiving yards against Nebraska early in the season.
"It started out with the Nebraska game and people around the world having a chance to see me," Edwards said. "It was a real good achievement when I broke Randy Moss' touchdown record (with 27) because as you know, Randy Moss was one of the best receivers to ever play football."
Edwards said it's as simple as believing in hard work.
"In the summertime, all I do is run routes and I watch a lot of film," Edwards said. "Plus, when you have one of the best quarterbacks (Tim Rattay) in the nation throwing to you, it makes your job kind of easy."
The awards show, sponsored by Home Depot, was televised live by ESPN2 from the Walt Disney World Resort.