The 20-year-old re-signed for the Vixens on loan from Chelsea for the Women's Super League One Spring Series, which begins on 22 April.
A Bristol City statement on Wednesday said: "A scan last week confirmed she has ruptured her ACL a few weeks ago."
The ex-England Under-19 striker scored 11 goals in all competitions in 2016.
Bristol City Women forward Mille Farrow is set for a spell on the sidelines after rupturing her anterior cruciate knee ligament in a friendly.