Background Health extension workers (HEWs) are the implementers of the unique primary health care programme of Ethiopia. They facilitate community participation in maternal health service delivery via the health development army (HDA) and pregnant women forums (PWFs). As part of a quality improvement intervention, HEWs received training, guidance and supervision focused on facilitation of HDA meetings and PWFs. We aimed to assess the effect of the intervention on maternal health service utilization and explore the perceptions of stakeholders regarding efforts to enhance community participation in maternal health. Methods We conducted a mixed method study in Shebedino woreda (district), Sidama Zone, southern Ethiopia. The research team observed HDA meetings and PWFs (15), conducted in-depth interviews with 32 HEWs, 8 HEW supervisors and maternal health program managers, and conducted 8 focus group discussions (FGDs) with community members. The interviews and FGDs were recorded, transcribed, translated, coded in Nvivo and thematically analysed. We also collected quantitative data on HDA and PWF participation, antenatal care attendance and skilled delivery and analysed using Excel (Microsoft Inc, Seattle, WA, USA). Results The proportion of HDA leaders and pregnant women who attended the HDA and PWF meetings increased by 30.6% and 36% respectively, over 18 months of the intervention. The percentage of pregnant women identified and referred by HDA leaders increased from 42% to 85%, the antenatal care utilization increased from 73.4% to 77.6% and skilled delivery increased from 76.7% to 83.3%,) (p<0.05). From interviews with stakeholders, we found improved awareness about maternal health services and increased health seeking behaviour. However, lack of incentives and reporting formats for HDA leaders, absenteeism and limited support from kebele administrators constrained community participation in maternal health. Conclusion With focused training, guidance and regular supportive supervision, HEWs were able to stimulate and enhance community participation, resulting in better maternal health service utilization in rural communities. HEWs, volunteer HDAs, pregnant women and the wider community have a role to play in quality improvement of maternal health services.