South African centre Stefan Watermeyer scored on his debut as Ospreys all but ended Welsh rivals Dragons hopes of progressing in the LV= Cup.
Watermeyer's contribution inspired Ospreys to their first LV= Cup win this season while Ross Jones, Hanno Dirksen and Eli Walker also touched down.
Dragons had been level at half-time thanks to wing Pat Leach's try and three Steffan Jones penalties.
But replacement Luke Williams' late try was their only second-half score.
Ospreys: R. Jones; Dirksen, Parker, Watermeyer, E. Walker; M. Morgan, Habberfield; Griffiths, Baldwin, Jarvis, Peers, Goode, O'Toole, Lewis, Allan, L. Morgan.
Replacements: L. Morgan for Watermeyer (56), Grabham for Habberfield (57), J. Thomas for Griffiths (70), S. Davies for Baldwin (70), Rees for Jarvis (30), S. Williams for Goode (69), Pitman for O'Toole (69), M. Davies for L. Morgan (70).
Sin Bin: O'Toole (59).
Newport Gwent Dragons: J. Smith; Harries, Tuilagi, Robling, Leach; S. Jones, Bedford; Price, Parry, Way, Cadman, Groves, Ellis, Waters, I. Jones.
Replacements: Buckley for J. Smith (50), L. Williams for S. Jones (58), J. Evans for Bedford (63), Coundley for Price (67), O'Driscoll for Parry (50), Jenkins for Way (67), Tyler for Cadman (50), Hodge for Ellis (67).
Referee: Mr D Richards (RFU).