Background Traditional antenatal care (ANC) models often do not meet women’s needs for information, counseling, and support, resulting in gaps in quality and coverage. Group ANC (GANC) provides an alternative, person-centered approach where pregnant women of similar gestational age meet with the same health provider for facilitated discussion. There are few studies that show associations between GANC and various outcomes. Methods We used mixed methods to evaluate a contextualized GANC model (Lea Mimba Pregnancy Clubs) and to understand implementation experiences at six health facilities in Kakamega County, Kenya. Between April 2018 and January 2019, we tracked 1,652 women who were assigned to 162 GANC cohorts to assess ANC retention. Using an intention-to-treat approach, we conducted baseline (N = 112) and endline surveys (N = 360) with women attending immunization visits to assess outcomes and used time diaries to assess wait times. At endline, we conducted 29 in-depth interviews (IDIs) and three focus group discussions with women who were currently and previously participating in GANC, and 15 IDIs with stakeholders. Results GANC was associated with enhanced social support, with some evidence for improved knowledge, adoption of healthy behaviors, enhanced self-efficacy, and improved experience of care. Quantitatively, we found strong associations between GANC and knowledge of danger signs, women who shared their feelings with other women, knowledge and competence of health workers, respect shown by ANC providers, overall quality of care, and birth preparations; as well as an improvement in ANC retention. No changes were seen in knowledge of positive behaviors, empowerment, several aspects related to women’s experience of care, ANC retention, early initiation of ANC, and other healthy behaviors. Qualitatively, women and stakeholders noted improved interactions between health providers and women, improved counseling, increased feelings of empowerment to ask questions and speak freely, and strengthened social networks and enhanced social cohesion among women. Both wait times and counseling times increased in GANC compared to traditional ANC. Conclusions This is one of the few mixed-methods studies evaluating GANC and offers new measures for experience of care, empowerment, and adoption of healthy behaviors. While more research is required, GANC holds promise for enhancing women’s experiences during pregnancy. Modifications are needed for sustainability and scalability.