After a slow start to the game the Portuguese idol netted his 25th and 26th Liga goals of the season to earn his team a hard-fought win over the Galicians.
The Celestes began impressively but wilted as Jose Mourinho's side asserted its superiority. Yet with Celta goalkeeper Javi Varas in fine form it was not until the 61st minute that the deadlock was broken through Cristiano Ronaldo.
Iago Aspas equalized for the home side after some shoddy defending just two minutes later, but Ronaldo wrapped up the win with a cool finish from the penalty spot.
Celta enjoyed a positive start to the game, with Aspas forcing Diego Lopez into action after just 15 seconds, and it took another two saves in quick succession from the keeper to keep things level in the 10th minute.
Aspas was again at the heart of the threat and it took a strong hand from the keeper to turn his cross-goal shot wide. The resultant corner was clipped deep to Alex Lopez but with his volley skidding towards the bottom corner, Lopez got across and held the ball.
The Celestes had been successful in holding a high defensive line but an Enrique de Lucas free kick that bent narrowly wide midway through the half proved to be a turning point.
Madrid soon gained fluency in the final third and pressed Abel Resino's men back. They were lucky that Ronaldo opted to square the ball when through on goal after 22 minutes, though Karim Benzema was also starting to find space to cause problems.
The Frenchman had two chances to beat Varas before the half hour mark but the keeper came out on top on both occasions.
Marcelo and Jose Callejon were both denied by some excellent goalkeeping from Varas before Ronaldo saw a header come crashing back off the bar in the 42nd minute.
Varas' impressive form continued after the restart as his strong hand kept Benzema's curling effort out and Marcelo fared no better as he blazed over the bar in the 57th minute.
Four minutes later, though, his resistance was broken. Luka Modric's corner was only partially cleared and when it came back into the area it fell to Ronaldo who somehow brought it under control and slotted into the net on the spin.
But the lead only lasted three minutes as some slack defending cost Mourinho's men dearly. Augusto Fernandez made use of a quick throw in to drill a low cross to Aspas who found the back of the net as his shot took a wicked deflection off of Pepe.
Lopez almost gifted Celta another goal as he spilled the ball in the area, but his side was back in front in the 72nd minute. Substitute Kaka was brought down inside the area Varas and Ronaldo chipped the penalty straight down the middle of the goal.
Gonzalo Higuain missed a pair of chances to add some gloss to the finish but Mourinho's blushes were truly spared in the last minute of normal time as Park Chu-Young's header hit the bar and went behind.
Los Merengues therefore temporarily move above their cross-city rival Atletico Madrid into second position, but that could change should Diego Simeone's men defeat Real Sociedad later on Sunday.