Two goals in three first-half minutes from Jimmy Kebe and Jobi McAnuff put the Royals in front before Noel Hunt got in on the act and extended the lead.
Andy King pulled a goal back for Leicester late on but it was nothing more than a consolation.
Rampant Reading, who were in the bottom half of the table just a couple of months ago, are now just three points adrift of second-placed Cardiff.
Leicester, meanwhile, are five points shy of the top six with four matches remaining after an untimely run of just two wins in the last 10 games.
Source: PA
Source: PA