Santiago Solari gave Isco a minimal role in his plans but, after Zidane was reappointed to end the Argentinian's ill-fated tenure, the Spain international returned to the starting XI alongside the similarly ostracised Bale, Marcelo and Keylor Navas.
Bale hit the crossbar and was fortunate not to be sent off, while Navas brilliantly prevented Maxi Gomez from putting relegation-threatened Celta ahead amid an all-action showing from Marcelo.
But it fell to Isco to break the deadlock after the hour and Bale made sure 13 minutes from time, moving Madrid two points behind city rivals Atletico in second ahead of their trip to Athletic Bilbao later on Saturday.
Navas, preferred to Thibaut Courtois in goal, made a stunning reaction save from Gomez's 16th-minute header and Celta retained a threat on the counter-attack throughout.
Bale struck a 30th-minute scissors kick against the bar and Sergio Ramos headed wide after Ruben Blanco diverted a rasping Marcelo strike behind.
The Wales forward crossed for Karim Benzema to roll into the net during first-half stoppage time but was correctly penalised for crashing an elbow into Kevin Vazquez's face and fortunate to only see a yellow card.
Unperturbed, Bale went sliding into Sofiane Boufal in the 53rd minute, the act of turning his studs to the turf before contact enough to spare him.
Modric thought he had given Madrid the lead when he drove home from Toni Kroos' partially cleared corner, only for a Raphael Varane to be ruled offside and interfering by a VAR review.
The breakthrough came after 61 minutes as Madrid constructed the type of sharp break that became a hallmark of Zidane's initial reign and Isco slid home Benzema's low cross before departing to a standing ovation.
Blanco excelled to thwart Bale and Benzema, but the former skipped through a flagging backline to clip in a right-footed shot off the post.
Madrid hit the right notes after Zidane gets the band back together
Julen Lopetegui and Solari might not have recognised the players who failed them but got back in the groove here. An extensive renovation job is expected at Madrid during the close-season, but Zidane has not lost the Midas touch when it comes to coaxing the best from those already in the building on this evidence.
Calm down, Gareth
Bale did not sulk under Solari, he got angry. The reappointment of a coach with whom he fell out of favour towards the end of last season meant his inclusion was a surprise. No Madrid player went closer to scoring before half-time and he wrapped up the points, but Bale could have been sent off twice. There are more level-headed ways – his friend Modric stands as an example – to show your commitment to the cause.
