Visiting Villa started the brighter of the two teams and they made the most of their domination with 11 minutes played.
Belgian international Benteke collected possession 25 yards from goal and, having turned to face the West Brom net, the 22-year-old sent a powerful effort beyond home goalkeeper Ben Foster.
Villa continued to provide a threat on the counter-attack and it was from one of those moves that they doubled their advantage.
Charles N'Zogbia picked out Agbonlahor from the right wing with a low pass. The striker's touch took him around West Brom defender Jonas Olsson and with his second he beat Foster from 10 yards out with 30 minutes played.
West Brom struggled to create anything in response, with their best effort being sent wide of the target by Graham Dorrans with three minutes of the half left to play.
As the half drew to a close, Eric Lichaj had an opportunity to put Villa 3-0 up, but Foster came off his line to smother the American's effort.
Should Villa hold out for all three points, they will move themselves up to 16th in the Premier League table.