Following earlier losses to Durham and Sheffield United, the Foxes are still searching for their opening victory of the new 2019/20 FA Women's Championship season.
With just 19 minutes on the clock, the hosts were ahead as Ylenia Priest finished powerfully from a Lionesses corner following a period of impressive early play.
After the break, Leanne Cowan doubled London City's advantage with an assured low drive from the edge of the penalty area in Dartford.
With five minutes to go, Flo Fyfe's effort crashed back off the Foxes' crossbar, falling favourably for Evie Clarke, who finished confidently to make it 3-0.
City were able to score a consolation goal, however, in the latter moments as new signing Simran Jhamat fired home at the near post to dent their hosts' advantage.
Leicester are next in action on Sunday 15 September (2pm BST kick-off) when they welcome London Bees to Farley Way.
The details:
City: Field, N. Johnson, Everett, Morgan (c), Cataldo, Smith, Paul, James, Dugmore (Thomas 86'), Bailey-Gayle (Blanchard 62'), Popple (Jhamat 70')
Subs not used: Nuttall, Brown, Taylor, L. Johnson
Goal: Jhamat 90'