Introduction <p>Gender-based violence (GBV), particularly intimate partner violence (IPV) and reproductive coercion (RC), is associated with poor reproductive and maternal health outcomes. Despite studies establishing the prevalence and severity of GBV across many settings, health settings largely lack systematic strategies to prevent and effectively respond to IPV and RC. Our study assessed the feasibility, appropriateness and acceptability of integrating GBV first-line response and counseling for IPV and RC in antenatal care (ANC) and family planning (FP) clinical settings in Nigeria.</p> Methods <p>A mixed methods study, embedded within a matched-pair, cluster-controlled trial, was used to examine the feasibility, appropriateness and acceptability of GBV screening and first-line response intervention, which adapted and combined the World Health Organization’s LIVES model and the Addressing Reproductive Coercion in the Health Setting (ARHCES) model in antenatal care (ANC) and family planning (FP) clinical settings in twenty health facilities in Ebonyi and Sokoto States, Nigeria. Seventy-five health providers (16 nurses-midwives and 59 Community Health Extension Workers) were trained on GBV first-line response and empowerment counseling and were mentored and followed over sixteen months. Provider surveys were collected at months one, three and nine, and a health facility quality assurance tool was administered pre-intervention, three months after the commencement of the intervention and at nine months. Additionally, we identified barriers to and facilitators of implementation through lessons learned from workshops with health providers.</p> Results <p>Quality assurance standards increased over time (<i>P</i> ≤ 0.05), demonstrating improved readiness for service availability and appropriateness, facility readiness and infrastructure, the availability of Information, Education and Communication (IEC) and visibility materials, appropriate systems, commodities and infrastructure. The pulse survey showed no significant change over time for feasibility, appropriateness and acceptability; however, service providers generally viewed the integration of GBV first-line response into ANC and FP as appropriate and acceptable, based on average scores of approximately 3 out of a maximum of 4. The “lessons learned workshop” indicated that providers initially perceived the intervention as additional work, but over time, it became part of their routine workflow, which they acknowledged improved their ability to provide quality GBV services. However, a lack of funds and limited staff resources were found to be key barriers to integration.</p> Conclusion <p>Our results showed that integrating GBV first-line support into ANC and FP services is broadly feasible, appropriate and acceptable in both Sokoto and Ebonyi States, Nigeria. However, modest declines observed in month nine indicate ongoing challenges and a need for continued mentoring and support. Hence, GBV integration should be scaled up across health facilities whilst making available human and financial resources with specific investments in staff capacity, ongoing supervision, and community engagement for continuous strengthening of GBV service provision in both states and Nigeria at large.</p>