The 42-year-old was approached by Martin O'Neill to work alongside him, despite the fact that he had previously fallen out with officials and some players during a bust-up at the 2002 World Cup.
However, the former Manchester United midfielder has revealed that he had no intention of turning down the opportunity.
"I've always had an open mind. It fell in nicely it was with Martin O'Neill and being back involved with the Irish team. [It was] too good to turn it down," he told reporters. "I would have been crazy to turn it down and there wasn't one bone in my body that thought this wasn't for me."
Keane and O'Neill have signed contracts with the Irish Football Association until the end of the 2016 European Championships qualifying campaign.