The hosts dominated the first half and deservedly took an early lead when Benzema curled in a precise finish.
Toni Kroos then added a second before the break as he finished off a neat move.
Valencia did not manage a shot on goal until the second half with Maxi Gomez testing Thibaut Courtois from distance.
The win means Real Madrid are five points behind leaders Atletico Madrid, who have two games in hand.
- Shots on Target
Source: bbc sports