Keane insisted he would not play for Ireland boss Mick McCarthy again following his World Cup walkout.
But McCarthy's departure on Tuesday has left the way clear for a comeback and McAteer claims the Manchester United captain would be welcomed back.
"I am a big fan of Roy Keane,'' said McAteer.
''He's a world-class player and we are going to benefit from having him.
"After all that has gone on between us, I do actually like Roy.
''What happened is part and parcel of football.
''I'm not going to walk away and say I hate Roy Keane for what happened because I don't.
''At the end of 90 minutes you shake each others' hand and get on with it."
McAteer and Keane had a much-publicised bust-up in August when Sunderland and Manchester United clashed in the Premiership in August.
It culminated in Keane receiving the red card for elbowing his fellow countryman.
McAteer had also had a dig at Keane over his controversial autobiography.
He said that he would "rather buy a Bob The Builder CD for my two-year-old son" than read a copy of Keane's book.
But McAteer is adamant that the Irish side is all the better for Keane's inclusion.
"You can never question Roy's commitment, talent or experience. But he made the decision to walk away from the World Cup," McAteer said.
''He had his own reasons, and whatever they were, the decision was up to him."