The striker headed home the second goal as the Foxes secured a 3-0 victory in the Championship.
Harry was in fine form and forced an early save from Rovers' goalkeeper Jake Kean before heading just wide.
Chris Wood opened the scoring after 29 minutes and Harry made it 2-0 just before half-time, rising well head home meet Ben Marshall's cross.
David, who completed the full 90 minutes for Rovers, tried his luck from distance in the first half but Leicester were in charge and Harry went close again in the second half before being substituted on 83 minutes. Andy King completed the scoring in injury time.
Nigel Pearson was pleased again with Harry's display. “I thought he played very well again tonight. He hasn’t played much football recently so for him to be able to manage the two games he has played shows he has a lot of football intelligence," he told lcfc.com.
In League Two, Jordan Archer started again as Wycombe ended a recent run of defeats with a 2-1 win at Torquay.