The 25-year-old striker, who celebrated his birthday on Monday, has agreed a new deal that will tie him to the Club until the summer of 2010.
Since arriving from Tottenham Hotspur in January 2004, Bobby has scored 26 goals in 79 league and cup appearances for the Club, including five strikes in just eight Premiership starts so far this season.
The lifelong Hammers fan, who trained with Hammers as a schoolboy before making his name at Brighton and Hove Albion ahead of a move to White Hart Lane in the summer of 2003, famously netted the winning goal in last year's Championship Play-Off final that sealed our promotion to the Premiership.
Manager Alan Pardew said: "It's fantastic news that Bobby has signed a new contract and I'm delighted that we have yet another of our young players committed for the long-term future.
"Bobby has made brilliant progress in the past 12 months and I'm very pleased with his contribution this season.
"He is a local boy who loves the Club, and I hope he will go on to enjoy a lot of success with us in the years to come."
A full and exclusive interview with Bobby will appear on whufc.com later today