The Croatian was dismissed by referee Mike Dean after remonstrating with the official at half-time during the Baggies loss at Everton.
Bilic was subsequently charged with improper conduct and could have faced a two-match touchline ban if evidence of abusive or insulting language had been found.
But after watching video footage of the incident, the FA instead deemed the incident minor and instead opted to fine the 52-year-old.
It means Bilic will be in the dugout tonight for Albion's League Cup clash with Brentford.
He will also be in charge for Saturday's visit of Chelsea.