In February 2003 on National Signing Day, Russell committed to Louisiana State University (LSU) over Florida State University, becoming the LSU Tigers' 28th and final recruit of the 2003 season. He redshirted his freshman year and by the fall of the 2005 season, Russell was the starting quarterback. He led the Tigers to a 10–1 regular season record, the Southeastern Conference (SEC) Western Division title, and a top five ranking going into the SEC Championship Game. He also improved statistically, completing 60 percent of his passes for 2,443 yards and 15 touchdowns. Russell received an honorable mention on the AP's All-SEC Team.