The Hammers grabbed their first win under David Moyes against the English top-flight champions at the London Stadium.
Marko Arnautovic’s sixth-minute strike was enough for the hosts to condemn the Blues to their first defeat in seven league games.
Masuaku, in his 11th league appearance this term, put up an outstanding display in his left wing-back role and was a thorn in the flesh of Chelsea's Davide Zappacosta.
And after putting up a Man of the Match display to help the Hammers seal their third league win of the season, the 24-year-old lauded his team’s performance and urged his teammates to keep improving.
“Huge team effort, special win for everyone at the club. Still a lot to do, need to keep our heads down and keep on working even harder. Nice recognition for me, but winning is always more important! Thank you all for your amazing support,” Masuaku tweeted.
West Ham United sit in 18th spot in the English Premier League table with 13 points from 16 games and will host Arsenal in their next league game on Wednesday.