The former Tranmere Rovers and Shrewsbury manager has agreed a deal to the summer of 2026 and will take over a team back on track.
"This is a hugely exciting opportunity at a wonderful football club and I am determined to deliver the success that everyone here craves," he told the club's website.
“The aspirations of the club and the developments in recent times mean it is a genuine privilege to be joining Oldham Athletic at this juncture. There is so much potential here and the scope to achieve something very special.
“The supporters of this club deserve success and together I want us to embark on a journey that will create lasting memories for us all.”
The Latics have been without a boss since parting company with David Unworth in mid-September.
Since taking over, Steve Thompson and Neil Redfearn guided the club on an unbeaten six game run, winning their first three against York City, Oxford City and Kidderminster Harrier followed by a trio of 1-1 draws.
The club confirmed on Thursday morning that they have left their position as the interim management team ahead of the new appointment.
Oldham face a tricky trip to Altrincham in the FA Cup this weekend before away games against Rochdale and AFC Fylde.