The Magpies suffered a 3-1 defeat to Chelsea away from home at Stamford Bridge in the Premier League.
During the match, Chelsea fans booed Benitez, who was in charge of the Blues from November 2012 until the end of the 2012-13 season.
In his spell at Stamford Bridge. the former Liverpool and Real Madrid manager guided the team to Europa League success.
Chelsea fans, though, never took to Benitez and booed the Spaniard during the match against Newcastle, something that the former Valencia boss was not aware of.
Benitez told The Daily Mail: “I didn't realise, I was just focused on the game.”
Newcastle were expected to lose to Chelsea and so they did, and they are now in danger of getting relegated to the Championship at the end of the season.
The Magpies’ recent results and performances have been disappointing, and they need to step up.