Fitzpatrick completed 12-of-26 passes while Spiller also chipped in with 59 rushing yards on 24 carries for the Bills (6-10), who snapped a three-game losing skid in the season finale for both teams.
The Jets' Mark Sanchez, meanwhile, wrapped up a rough season by managing to complete just 17-of-35 passes, throwing an interception and losing a fumble.
New York (6-10) got 74 rushing yards on 19 carries from Shonn Greene in the setback.
Notable deaths of 2014 [PHOTOS]
Julius Randle breaks leg during NBA debut