The 23-year-old, fresh from helping Wales defend their Six Nations title, played 72 minutes at the Liberty Stadium, scoring one of Ospreys' seven tries in the bonus-point win.
Biggar touched down the fifth just after the hour mark and also contributed 13 points with the boot - five conversions and a penalty - against the Dragons.
Despite Scarlets, who started the evening in fourth place in the RaboDirect PRO12 table, defeating Zebre 24-10, Ospreys' bonus-point win ensured the two team's swapped placesin the table.
They are both level on 54 points and fly-half Biggar admitted he had no intention of sitting out the clash against the Dragons with play-off places still up for grabs.
"I never had any thoughts of resting and missing the game. It was awesome to come back and play, we get paid here, so no rest and it was good to get back," said Biggar.
"It was nice to score a few points again and if I can do my bit to help the team then great
"We were a little bit loose, I think we got carried away with the amount of ball we had, we had a little bit of a row at half-time for being a little bit loose.
"But we tightened things up, finished of our fourth try but then got a little bit loose again. But it is not a bad hit out considering we have only just come back."
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