The full-back was suspended by Sunderland over a comment posted on the social media site Instagram after the 1-0 Premier League defeat at home to Fulham which read: "Great opening day. Hahahhahaha hahahhaha!!!".
But the 28-year-old has admitted he was wrong to post the message and his exile has ended, although he may have to wait before forcing his way back into manager Paolo Di Canio's plans as he recovers from a broken foot.
"I would like to apologise to the club and supporters for my comments made on social media," he said in a statement.
"I understand how they may have been interpreted and it was a serious error of judgement.
"I accept the punishment that has been handed to me by the football club and will now focus my attention and efforts on rehabilitation and regaining my fitness."
Bardsley has cut a controversial figure in recent months, with Di Canio criticising him publically after he was photographed at a casino in May.
That led to the player being forced to train with the club's U21s during the summer.
A proposed move to Fulham then broke down when he suffered his injury, but he has now been given the opportunity to re-establish himself at the Stadium of Light.