The Swansea-based region had lost in the last three clashes against the Dragons but the South African centre inspired a victory, which ended the Men of Gwent’s chance of progress in the tournament.
Ross Jones, Hanno Dirksen and Eli Walker also touched down for the hosts, who were playing at the Brewery Field in Bridgend.
The Dragons entered the interval tied at 14-all following a try from returning wing Pat Leach and three penalties from the boot of Steffan Jones.
But the Ospreys pulled away in the second-half before the Dragons clinched a late consolation try from Luke Williams.
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