The 22-year-old became the club's fourth new striker of the summer after joining from Peterborough, and his new manager is happy to have got his man.
"David is an exciting young talent who I've been chasing for two and a half months," he told the club's official website fleetwoodtownfc.com. "I am delighted to add such a quality footballer to the squad.
"He has unbelievable promise and is the type of talent that we want to develop at the football club, alongside the experienced players that we have already brought in."
The former Manchester City youngster, who has signed a three-year deal, stated that Mellon's style of football was a big factor in him joining the club.
"I've heard a lot about Fleetwood's progress through the leagues and the really good football that they have played along the way," he said.
"The way the manager wants to play suits me and I can't wait to start. I've joined a club that is moving forward and to become a part of that is really exciting for me."