The Portugal star's first-half header and a brilliant strike from the full-back set the hosts on their way before a disastrous own goal compounded the 10-man visitors' misery
The Portugal attacker buried a first-half header to set the hosts on their way before teeing up the Brazilian for a brilliant right-footed strike to double the advantage shortly after the break.
Levante - who had David Navarro sent off for a crude challenge from behind on Ronaldo - then further compounded their own misery as Nikos Karabelas scored a bizarre own goal to hand Carlo Ancelotti's a third in their 16th-straight win at Santiago Bernabeu.
The visitors came into the game having conceded just one goal in their previous five games, but their backline was put to the test early on in a strong spell of Real pressure.
Ronaldo was the first to test Keylor Navas with a side-footed effort on the volley from inside the area and the forward then put Real ahead after just 11 minutes.
He rose highest to head home an Angel Di Maria corner and move to 38 goals for the season in all competitions.
Andreas Ivanschitz volleyed over from outside the area when Levante carved out their first opportunity.
That proved a rare period of respite as Gareth Bale and Karim Benzema linked shortly after, leading to Navas thwarting the Frenchman from close range.
Di Maria flashed an effort wide from distance as Real continued to probe and Benzema almost doubled the lead shortly before the break, but Navas continued his heroics by tipping a header onto his right-hand post and wide.
Ronaldo turned provider for the second, which saw Marcelo shimmy past Navarro, cut onto his right foot and fire past a helpess Navas to record his first league goal since January 2012.
Keylor was again called into action to deny Benzema before Levante were reduced to 10 men as a result of Navarro's late challenge from behind on Ronaldo.
Karabelas inadvertently swept Marcelo's cross into his own net to put the result beyond any doubt nine minutes from time as Madrid moved three points clear at the summit of La Liga.