Four goals from Ella Toone headlined a ruthless performance from the visitors in Quorn, while Kirsty Hanson, Alex Greenwood, and a Nat Johnson own goal sealed all three points for United.
It was in fact City who enjoyed the best of the early action as Ella Franklin-Fraiture found Melissa Johnson in a pocket of space, but Siobhan Chamberlain was quick off her line to curtail the danger.
In the 14th minute, though, United were ahead as Toone capitalised on a loose ball to give them the lead before adding another just two minutes later by latching onto an incisive pass from Mollie Green.
Before the break, Kirsty Hanson, meanwhile, made an effective run down the right flank for United and went for goal just outside the box, but Foxes goalkeeper Demi Lambourne was able to block the shot.
While the visitors were awarded a penalty before half-time, Katie Zelem’s spot-kick was saved brilliantly by Lambourne. However, it would turn out to be City’s highlight of the evening.
Two goals in quick succession, in the 51st and 53rd minutes respectively, confirmed United’s dominance as Hanson and visiting captain Greenwood make it 4-0.
A second penalty came their way 12 minutes later and Toone completed her hat-trick and netted United’s fifth.
While Johnson’s own goal, with eight minutes to play, added another to United’s impressive goal tally, Toone added her fourth and her side’s seventh in the latter moments.
Following this result, Leicester remain sixth in the FA Women’s Championship, with 10 points from 15 matches, and head to Tottenham Hotspur next Wednesday (7:45pm GMT kick-off).
The details…
City: Lambourne, Franklin-Fraiture, Jackson, Nymoen (Thomas 82’), Morgan (c), Domingo, M. Johnson (Greengrass 64’), James, Dugmore, N. Johnson, L. Johnson (Axten 45’)
Subs not used: Clarke, Ayisi, Brown, Worts