Steve Clarke masterminded a win over his former club but the same could not be said for former Baggies boss Roberto Di Matteo who is in the middle of his worst spell as Chelsea manager.
The Italian found his side behind after 10 minutes when James Morrison's cross found Shane Long who bundled in a header at the far post, his fourth goal of the season.
Chelsea had almost taken the lead prior to Long's opener when Ryan Bertrand's shot was cleared off the line by Liam Ridgewell but that was the closest the visitors came to beating Boaz Myhill for most of the first-half.
The European Champions did find an equaliser before half-time when Eden Hazard's header was helped into the back of the net by Billy Jones but they found themselves behind after the restart when Odemwingie headed home Long's cross at the near post.
Second-half substitutes Oscar and Juan Mata turned the game in Chelsea's favour but the visitors failed to equalise for a second time with
Daniel Sturridge left frustrated in front of goal. The England forward forced multiple spectacular saves out of Myhill before drilling a low shot wide in the closing stages of the game.
West Brom are now on their best start to a top-flight campaign in over 30 years and sit in fourth place, just one point behind European Champions Chelsea.