The Brazilian striker has been in fine form this season, and now has 12 goals in 22 Primeira Liga appearances after he came up with the goods again to bolster Maritimo's hopes of European qualification.
His strike, which came after a Joao Diogo own goal had looked set to hand Vitoria a point after Theo Lewis Weeks' first-half opener, also ensured Pedro Martins' charges bounced back from their embarrassing 3-1 defeat to bottom side Pacos de Ferreira last week.
Weeks broke the deadlock after 33 minutes, latching onto Derley's header after Vitoria keeper Assis flapped at a lofted cross.
However, they were pegged back by an own goal from Diogo shortly before the hour mark.
Following a dangerous delivery across the face of goal, Chris Malonga looked set to tap home for the visitors before Diogo beat him to it - turning the ball into his own net to level the scores.
However, Derley popped up with a header 14 minutes from time to seal all three points for Martins' men and move them level with Vitoria and Sporting Braga in the table.
