The striker, 19 has spent his entire career with the Hammers, coming up through the youth team ranks before making his first-team debut 15 months ago.
He came on for the final 16 minutes of the March 2008 clash with Blackburn Rovers and headed home the winner.
Last season Sears, who has already represented England at Under-19 and 20 level, made 22 Premier League appearances for the club, most of them from the substitute's bench, but failed to find the net again.