Head coach Bob Stoops made the official announcement Tuesday afternoon that Saunders, a first-team All-WAC selection in 2011, has joined the Sooners.
"We are excited to add an explosive player in Jalen to our program," Stoops said. "He has great speed as evident by his yards-per-catch average and is someone who can contribute to our program in a number of ways."
Saunders finished second in the country last year with his 21.4 yards-per-reception and racked up 10 passes that spanned at least 44 yards or longer.
He led the WAC with 12 touchdown receptions, and six of those 12 were 50 yards or longer.
The 5-foot-9, 160-pound wideout led his team with 1,065 receiving yards on 50 catches and posted the program's ninth 1,000-yard season in the process.
Saunders also ranked second on the team in rushing last season, netting 91 yards on eight carries, and he reached the end zone on the ground or in the air in 10 of his 13 contests.
His freshman season back in 2010, Saunders was third for Fresno State with 27 catches for 441 yards and three touchdowns.
That year he also rushed for 109 yards on 14 carries.
Because of NCAA transfer rules, Saunders will have to sit the 2012 season, but will be eligible as a redshirt junior in 2013.