The Nigeria international failed to make his mark at the Baggies after signing in 2014 for a then club-record 10 million pounds, and has now moved to Greece.
Brown Ideye has left West Brom to join Olympiakos for an undisclosed fee.
The 26-year-old scored just four goals in 26 league appearances for the Baggies after joining in July 2014 from Dynamo Kyiv for a then club-record 10 million pounds ($15.4M), but failed to live up to his price tag at The Hawthorns.
Ideye's move to the reigning Greek champions was finalized in time for him to be registered in their Champions League squad, where they face Bayern, Arsenal and Dinamo Zagreb in Group F.