Irons was held out of Saturday's 38-7 Auburn victory over the University of Buffalo.
"Kenny Irons is full speed," Auburn head coach Tommy Tuberville said. "He could have played yesterday. We just needed to get Brad Lester in the game."
Irons had been slowed with groin injury and a toe problem, but was on the sideline at Saturday's game ready to play if needed.
Two other starters who missed Saturday's contest are scheduled to play on Thursday night vs. South Carolina. Senior linebacker Karibi Dede and junior cornerback Jonathan Wilhite are cleared for action.
"Jonathan Wilhite will be back," Tuberville said. "He is about 95 percent and will practice today."
The Tigers, 4-0, will play on Thursday night at South Carolina. The Gamecocks are 3-1 overall and 1-1 in the SEC. Auburn is 2-0 in the SEC.
Tuberville said he agreed to play the game on Thursday night with a short turn-around because he believes it is the right thing today.
"We have got a good television contract in the league," Tuberville said. "I believe everybody is responsible for taking a turn playing (on Thursday) to give ourselves an opportunity to enhance our TV contract."
He added that with 12 games on the schedule and no off week the Tigers can take several days off following the South Carolina game "to try to get their legs back before we play our next conference game."
Also on Tuberville said that after grading videos of Saturday's games that senior cornerback David Irons was named the coaching staff's defensive player of the week and guard Ben Grubbs was the offensive player of the week. Kickoff specialist Matt Clark won the big team award.