The North Walians started brightly before the Ospreys took the lead with the first of three penalties from last season's Wales Under 18 outside half Matthew Morgan.
The outstanding pivot, who finished the game with 25 points, crossed for a try after 16 minutes and after converting that, played a leading role in Oliver Pardoe's first try of the season.
Outside centre Eli Walker outsprinted the cover defence to score a third Ospreys' try two minutes after the interval, but to their credit the Gogledd Cymru side upped the tempo with Jake Simm ( Mold ) and Gareth Morgan ( Ruthin ) both in fine form.
Scrum-half Alex Schwarz was able to burrow over from a few feet out to register his side's first points of the new season, whilst Tom Parry ( Pwllheli) bagged a second home try five minutes later.
However, it was the Ospreys who had the final word - No.8 Dan Baker scoring under the posts.