Dummett spent the first half of the season on loan at the Clydesdale Bank Premier League side, featuring in 19 games, before returning to St James' Park at the turn of the year.
It had been expected that the player, who made his Magpies debut in their FA Cup defeat to Brighton earlier this month but is out of contract in the summer, would be on his way back to Scotland in time for the Hampden clash with the Hoops last Sunday.
St Mirren boss Danny Lennon was initially forced to admit defeat in his attempts to bring back Dummett for a second loan spell to when it emerged Pardew had had a change of heart.
However, Dummett's representative Spencer Downey has indicated the Buddies' 3-2 win over Celtic convinced Newcastle boss Alan Pardew that St Mirren was the correct place for the player to continue his development.
Downey told Press Association Sport: "Alan watched the game last week and that was what made his mind up to send Paul back to Paisley.
"Paul has come on leaps and bounds since he moved up here and the club were keen for him to continue down that road.
"There was speculation he could have gone to Leeds or a League One club on an emergency loan but it was decided St Mirren was the best place for him.
"Alan has also made a few signings and is now a lot more comfortable with his squad, so that helped too.
"Paul is delighted. He really enjoyed his first six months at the club and is now looking forward to winning his place back before the League Cup final."