Background Lesbian, bisexual+ and queer (LBQ+) cisgender women have considerable unmet mental health needs. The aims of this study were to examine LBQ+ cisgender women’s prior engagement with general practitioners (GPs), and how this relationship shaped their mental health service use. Method Data from 2707 cisgender LBQ+ women were drawn from a national survey of adults who are lesbian, gay, bisexual, trans, intersex, queer or questioning, asexual and other diverse sexuality and gender identities (LGBTIQA+) in Australia. Multivariable logistic regression analyses examined demographic predictors of continuity of care with GPs and GPs’ awareness of LBQ+ women’s sexual orientation. The relationship between these variables and recent mental health service use was then analysed, comparing LBQ+ women’s engagement with services known to be LGBTIQA+ inclusive and those without an inclusive reputation. Results LBQ+ cisgender women with a regular GP had greater odds of having accessed mental health services in the last 12 months. Two-thirds had a regular GP, with the lowest odds among women aged 18–35 years and highest odds among women with a disability. LBQ+ women who did not believe their regular GP knew of their sexuality had lower odds of having accessed LGBTIQA+ inclusive mental health services. These individuals were typically aged below 25 years, bisexual+ or queer identified, had below undergraduate-level education, earned <$2000 AUD per week, or lived in an outer-suburban or regional area. Conclusion GPs may be missing opportunities to promote continuity of care through developing trusting relationships with specific sub-populations of LBQ+ women, which in turn appears to sustain inequitable access to mental health care. To offer appropriate care and referrals for this population, GPs should provide safe and inclusive environments to enable comfortable and supportive discussions about sexual orientation when this is relevant to a person’s health care.