Richards, on-loan from fellow play-off hopefuls Northampton Town, came on for the injured Paul Tait midway through the first half and opened his account just after the break when he raced onto a Rickie Lambert pass before rounding keeper Glen Morris and slotting the ball into an empty net.
Richards doubled his team's lead 12 minutes later when a Gary Jones header exposed a huge gap through the middle of the Leyton Orient rearguard which left him clear on goal to pick his spot from 20 yards.
In the first half although Rochdale huffed and puffed they failed to take advantage of the fact that they were enjoying the lion's share of the play and clearly missed suspended leading scorer Grant Holt as they failed to take advantage of a poor O's defence.
Tait had to be subbed after a clash with keeper Morris had left him with an eight-inch gash in his forehead that needed 12 stitches.
Leyton Orient's only chance of the game came after three minutes when midfielder Daryl McMahon tried his luck from distance and was unlucky to see his curling 35-yard drive bounce back off the bar with keeper Matthew Gilks clawing at thin air.
In the final stages Rochdale had a further injury problem when defender Gareth Griffiths picked up a neck injury that may well leave him doubtful for next week's game against Shrewsbury that will see Steve Parkin's side looking to extend an unbeaten home record that dates back to October 16.