The Hammers failed to return to Premier League action after the two-week international break with a victory, going down 2-1 to relegation-threatened Leicester away from home.
The hosts took the lead as early as the 12th minute when former Inter Milan midfielder Esteban Cambiasso fired home from 20 yards.
David Nugent had a penalty saved for the Foxes at the King Power Stadium soon after, and the home team failed to prevent Chiekhou Kouyate from scoring the equaliser just past the half-hour mark.
Although West Ham tried to find the winner in the second with Kouyate hitting the post, it was Leicester who picked up the points from this Premier League encounter.
Substitute Andy King turned in Jamie Vardy's mis-hit shot in the 86th minute to ascertain Leicester’s first win in nine Premier League matches.
After the defeat, West Ham duo Adrian and Poyet posted the following messages on Twitter.
Back to London without get anything today!Football is goals and we missed too much chances to score...Just keep working for next home game ⚒— Adrián San Miguel (@AdriSanMiguel) April 4, 2015
Disappointing result today, hopefully we can bounce back next week at home— Diego Poyet (@diegopoyet7) April 4, 2015
West Ham are currently ninth in the Premier League table with 42 points from 31 matches.