The game, which was played inside the San Pedro de Alcantara in Marbella, was part of Wolfsburg’s preparation ahead of the second half of the Bundesliga season which will resume on Friday, January 12.
St. Pauli took the lead in the fifth minute but Wolfsburg equalised in the 12th minute through Jeffrey Bruma.
In the 27th minute, Osimhen, 19, put Wolfsburg 2-1 up before Daniel Didavi wrapped the game up with eight minutes remaining.
Wolfsburg’s next friendly game is against another Bundesliga 2 side Dynamo Dresden on Saturday also at the same venue.
They will travel away to face Borussia Dortmund in their first game in the second stanza of the current Bundesliga season on Sunday, January 14.
They are currently 12th on 19 points in the 18-club league table.
Osimhen has played five league games for Wolfsburg this season but is yet to find the back of the net.