Getafe goalkeeper Oscar Ustari was powerless to prevent his 13th-minute strike from the edge of the penalty area arrowing into the top corner.
Ronaldo almost doubled the visitors' lead five minutes later when he cut in from the left but Ustari tipped his fierce long-range drive over the bar.
Two clinical finishes from in-form Higuain put Real three goals ahead inside 23 minutes, taking the Argentinian's tally to 22 league goals this season.
Higuain picked up Rafael van der Vaart's streaking pass and beat Ustari with a low shot before later rounding the helpless keeper for his second and tapped into the empty net after smart work from Fernando Gago.
Ronaldo made it four goals for a rampant Real in the 37th minute, dancing inside from the right wing and smashing an angled shot into the roof of the net.
Daniel Parejo pulled a goal back a minute later when Real keeper Iker Casillas raced out of his area to clear. The Getafe midfielder clashed with the Spain captain, robbing him of the ball before weaving through a crowd of defenders into an empty net.
|Ronaldo scored Real's fourth, hammering the ball home after cutting in from the right [AFP]
Casillas was furious with the referee for not penalising Parejo's challenge and needed lengthy treatment on his ankle before seeing out the match.
Real comfortably controlled a much less frantic second half, although Casillas was beaten again in the 80th minute when Pedro Leon pounced on a loose ball and finished from close range.
Getafe's miserable night took a turn for the worse in added time when coach Michel, a former Real player, was dismissed from the bench for protesting a decision.
It was Real's 10th consecutive La Liga victory and they set a new club record of scoring three or more goals in nine straight matches, beating a mark from the 1951-52 season.
"The important thing was the victory," Higuain said after the game. "I'm very happy, but on Sunday we have another very important match that we have to win."
Real host Atletico Madrid, who won 2-0 at home to Athletic Bilbao in Thursday's late kickoff, at the Bernabeu on Sunday.
Diego Forlan swept home a Juan Valera cross in the 54th minute and Sergio Aguero pounced in the 86th to lift erratic Atletico, the only side to beat Barca this season, up to eighth.
Real and Barca are 18 points clear of third-placed Valencia, who beat Malaga 1-0 on Wednesday to move to 53 points, and Real Mallorca are six behind Valencia in fourth.