The teenager was found down the right-hand side of the Celta Vigo area - utilising his pace to get the better of his defender - before the La Fabrica graduate unleashed a low shot across the face of goal which got the better of the Celticos shot-stopper's somewhat lackadaisical efforts.
Isco floated a pass deep into Celta's problem left channel, where a rampant Bale cut inside by nutmegging Jonny and lashed into the top corner from a narrow angle.
Celta Vigo were on the front foot early on and almost opened the scoring in the ninth minute through Lucas Boye, but Keylor Navas made a great stop.
However, refusing to be outdone by his Welsh team-mate, Isco soon got in on the act with his own majestic strike from the edge of the area to give Real Madrid a well-deserved three-goal cushion with what was nearly a carbon copy of Bale's, although on the other side of the area, just two minutes earlier. There was to be no hat-trick for Bale, however, with the Welshman replaced in the 72nd minute of the contest.
Real Madrid will finish their La Liga campaign away to Villarreal next weekend, while Celta, who remain down in 13th position in the table, will end at home to Levante.