Real Madrid's goals were scored by Kylian Mbappe (two goals), in the 19th minute from a penalty kick and in the 31st minute from an assist by Arda Guler.
Jude Bellingham added the third goal in the 44th minute, before Alvaro Carreras completed the rout in the 82nd minute.
Real Madrid increased their points tally to 30, strengthening their lead in the Spanish league standings, and are now seven points ahead of their new runner-up, Villarreal, who snatched second place after their resounding 4-0 victory over Rayo Vallecano in a match played earlier on Saturday.
Barcelona, the defending champions, have dropped to third place with 22 points, but they could regain second place and reduce the gap with Real Madrid to five points if they beat their guest Elche later today, Sunday, in the same round of matches.
In contrast, Valencia remains in 18th place with 19 points, having suffered its sixth defeat this season.
