He led Curzon Ashton to the NPL title in 2014/15 and they have remained in National League North ever since, and were still under his stewardship until his departure in November 2018.
A former Stockport, Hyde, Stalybridge and Droylsden player, Flanagan is no stranger to Seel Park having had a spell as assistant to Chris Willcock and then spent the second half of the 2009/10 as manager following Willcock’s departure.
Mossley’s club website said: “Curzon's loss is invariably Mossley's gain. Welcome back John!”
Flanagan led Curzon to the club’s best ever finish of 11th in National League North in 2015/16, and then the following season took them on their best ever FA Cup run, where they reached the second round and were beaten 4-3 in a thriller against AFC Wimbledon.
Mossley opened up their pre-season campaign with a 1-0 win at Rhyl on Saturday, Will Ozono scoring the winner.