Bruno Andrade handed the visitors the lead after just nine minutes, cutting inside Alan Goodall before shooting low across Scott Davies in the Fleetwood goal.
Wycombe could have doubled their advantage before the break, Davies with a vital save to deny Dean Morgan. Joel Grant then almost picked out Andrade at the back post but the tricky winger, at full stretch, was unable to connect to double his tally.
Town made two changes after the break and could have pulled level on the hour mark when David Ball was released in the Wycombe box by Shaun Beeley and his shot was deflected just wide.
Steven Gillespie rattled the woodwork as Fleetwood searched for an equaliser, while at the other end Morgan and Andrade both tested Davies again.
A late rally from Fleetwood proved too little too late as substitute Jamie Milligan's shot was blocked on the line and then Alex Marrow headed wide deep into injury time.