Christian Benteke opened the scoring, firing an unstoppable rising shot past Albion goalkeeper Ben Foster before Gabriel Agbonlahor doubled Villa's lead before half-time with a low drive into the corner of the net.
QPR transfer-window target Odemwingie equalised seven minutes from time when Gareth McAuley headed a Brunt corner back across goal and the lively Odemwingie reacted first and volleyed past Guzan.
Villa dominated the opening 45 minutes with Charles N'Zogbia in superb form as he produced one of his best performances for the Midlands club, providing the assist for both goals.
Agbonlahor has had a habit of scoring in local derbies and also looked back to his best as Villa controlled proceedings.
But Albion were transformed after the break – no doubt after a half-time rocket from head coach Steve Clarke.