Kaine Lewis was in the away end when he was spotted by officers at Albion's home fixture against Millwall in September.
The 34-year-old's actions were being aimed towards the home fans and Lewis was removed from The Hawthorns and arrested.
Lewis initially denied any wrong-doing and an investigation was carried out by West Midlands Police's dedicated football hate crime officer Pc Stuart Ward.
CCTV showed him making racist gestures which supported the accounts of officers on duty that day, which led to Lewis admitting to his behaviour at his first appearance at Dudley Magistrates Court.
Lewis, from Kent, was given a five-year banning order, a suspended four-month prison term and was ordered to carry out 200 hours unpaid work.
Pc Ward said: "This was not only disgusting behaviour but distressing for others who were at the stadium to see and hear.
"Lewis is old enough to know this is unacceptable and there's no excuse for such appalling actions.
"We won't tolerate racism, or any form of hate crime, within stadiums and we'll continue to take action against offenders."
There was also trouble outside the stadium during West Brom's 1-1 draw with Millwall, with a brawl breaking out near a fence separating home and away fans which was torn down.