Porter, in his fifth year as running backs coach at LSU, is also assistant head coach and chief recruiter on Les Miles' staff in Baton Rouge.
Washington Redskins secondary coach Jerry Gray had been a favorite for the job, but Memphis apparently chose to go in another direction.
Saturday, Gray said "one day it will be the right opportunity" to be a head coach.
Porter, a former Memphis player, was considered the lead candidate to replace Tommy West early in the process. Memphis (2-10, 1-7 Conference USA) fired West on Nov. 9.
Gray emerged as a favorite largely on the support of Memphis booster Fred Smith, the founder of Memphis-based Federal Express. Former Redskins coach Joe Gibbs recommended Gray and it was expected he would be Memphis' choice.
Memphis officials, according to The Associated Press, have scheduled a Sunday news conference, but athletic department spokesman Bob Winn said Saturday only that the announcement "pertains to the football program."
LSU beat Arkansas 33-30 in overtime on Saturday night.
Joe Schad covers college football for ESPN. Information from The Associated Press was used in this report.