The 35-year-old holds a Uefa Pro Licence and will officially become boss on June 1, with Dean Holden serving as his assistant manager.
It will be his first managerial role and the Irishman is honoured to take over at SportsDirect.com Park.
"I am delighted that the board of Oldham Athletic have seen fit to appoint me as the club's new manager," he said.
"It is a role that I accept with immense pride and one which I am fully focused on and committed to.
"As well as a wealth of playing and coaching experience, I pledge to Oldham and its supporters unwavering commitment and a desire to succeed. I am looking forward to building on the achievements of Oldham Athletic and driving the club to new levels of success.
"I ask the Oldham fans to believe in me and get behind the club whole-heartedly as we embark on an exciting new era. I will take this club forward, I can understand supporters' frustration but every expert had to start somewhere.
"If I didn't think I could do a good job, I wouldn't be here. We need bums on seats and I firmly believe we will move forward.
"It's a massive challenge and I am a massive risk, but I will have a creative style of play and we will play attractive football.
"I want to meet the fans, put myself into the lion's den and prove that I am worthy of this job role."