Fleetwood, currently outside of the relegation zone on goal difference alone, have moved to bring in experienced boss Sheridan ready for Saturday's game against MK Dons.
Sheridan has previously managed Chesterfield, Plymouth Argyle, Newport County, Notts County and Oldham Athletic, bringing an end to his fifth spell at the latter of those clubs in September.
Speaking to Fleetwood's official website, chairman Andy Pilley said: "John is exactly the sort of character we need at Fleetwood Town in the current situation. He has a proven track record of having an instant impact with clubs and we are confident that will be the case here.
"We have found ourselves in a difficult position in League One and it was important we appointed someone quickly to address this. John is here until the end of the season, at which point we'll review the situation again, it's an agreement which suits both parties at this time.
"I'd like to welcome him to Highbury and can assure him he'll have the full backing of all the players, staff and supporters to keep ourselves in League One."
Fleetwood's most recent victory came at Southend United six weeks ago.