Griggs has been suspended indefinitely by the university on Aug. 11 for what the school termed a “student conduct matter.”
While serving the suspension, Griggs did not practice nor was he involved in any team activities. The university, citing school policy, did not comment on Griggs’ reinstatement.
The Golden Eagles split their first two games without Griggs, rolling to a 55-7 victory over Jackson State in the season opener before dropping a 21-20 decision to Louisiana-Monroe.
Southern Miss (1-1) was scheduled to play at Appalachian State on Saturday but the game was postponed due to weather concerns related to Hurricane Florence. The schools have yet to reschedule the contest.
Sophomore Jack Abraham, a former Gatorade Player of the Year in Mississippi, started the first two games for the Golden Eagles, throwing for 620 yards with six touchdown passes and a pair of interceptions.
Last season, Griggs appeared in 10 games, making seven starts, for Southern Miss. He passed for 1,879 yards while throwing for 16 touchdowns versus only two interceptions.
The 6-foot-3, 225-pound Griggs also is a threat to run, rushing for 268 yards and three touchdowns in 2017.
Griggs sat out spring practice while rehabbing from surgery on his Achilles, according to the newspaper.