BACKGROUND: Pre-exposure prophylaxis is a highly effective method of HIV prevention but few women know about it, have access to it, or see it as relevant to them. In 2019, grassroots organization PrEPster piloted a peer-led intervention, MobPrESH (Mobilizing for Pre-Exposure prophylaxis (PrEP) and Sexual Health), across three sites in England, to mobilize for PrEP and sexual health with communities of women and non-binary people most affected by HIV, including Black women and non-binary people, people of colour, migrants, and transgender (trans) women. OBJECTIVES: We aimed to explore the accessibility, feasibility, acceptability, and 'fidelity' of MobPrESH, from the perspectives of peer mobilizers and project staff. METHODS: We conducted focus group discussions and qualitative interviews with nine peer mobilizers (most identified as Black cisgender (cis) women) and six project staff (including Black and white cis women and non-binary people). We analysed data thematically, iteratively, and inductively, informed by concepts of reproductive and social justice. RESULTS: We present findings in five thematic areas: connecting and relating to situate sexual health discussions, navigating silence and stigma, connecting within and across communities, competing pressures and structural hostilities, and resources and continuity. Community knowledge-building about PrEP is a slow, iterative process that needs investment and creation of trusted spaces that centre communities' needs and concerns. Peer mobilizers and the communities they engaged with had competing demands in their lives, and knowledge-raising about PrEP was impacted by intersecting stigmas, discrimination, and oppressions around HIV status, racism, misogyny, transphobia, homophobia, and anti-sex worker rhetoric. CONCLUSIONS: Peer-led PrEP interventions require funding and foregrounding, particularly for women and non-binary people who are Black, trans, migrants, and people of colour, situated relative to their wider health needs, life pressures, and priorities. This requires concurrent challenge of the racist and patriarchal structures that continue to obscure the sexual and reproductive health needs of racially minoritized and marginalized women and non-binary people.