Lucy Bronze's header towards the end proved to be the only goal of a closely fought game in which United arguably deserved more after creating a number of good opportunities to score.
The result, combined with Arsenal's defeat to Aston Villa earlier in the evening, means that Chelsea sealed the WSL title for the sixth straight season when the full-time whistle sounded.
United, who remain third, had been hoping to seal Champions League qualification with victory in this one. But now a point against Manchester City next time out would mathematically ensure a second top-three WSL finish in the space of three seasons.