Fleetwood's prowess in front of goal saw him score 30 goals in all competitions before the turn of the year and he attracted a lot of interest from other clubs, including Gillingham and Cheltenham.
His decision means Forest Green miss out on the £200,000 fee agreed with Crewe, but the Blue Square Premier club has welcomed his decision to stay.
"Neither the Board or myself would ever stand in the way of any player progressing up the football ladder," said delighted manager Jim Harvey.
"On this occasion we may have missed out on a massive windfall. It shows how genuine Stuart is and knowing the lad as I do, I know his word is his bond."
Fleetwood has now insisted he will stay with Forest Green until the end of the season, regardless of any offers which come in for him before the January transfer window closes.
"I can honestly state that even if any other clubs come in with a late bid before the transfer window closes, I am not interested," said Fleetwood.
"The summer may be a different matter but I owe a debt of gratitude to the gaffer and I am committed with my team mates to making this the best ever season that the club have experienced in their history."