Despite a large literature on integration of health services, there is a dearth of scholarship assessing service integration in its totality at the community level. Similarly, across the wide evidence base on community health workers (CHWs), there is little that analyses the ways in which they interact with both formal and informal structures and how these interactions shape their agency and ultimately the delivery of integrated services. A better understanding of agency in the work of CHWs would help health systems, policy makers and practitioners to better design and support the delivery of community-level integrated health packages to improve health outcomes. In this study, we explored the agency of CHWs in Malawi known as Health Surveillance Assistants (HSAs). We used qualitative methods: participant observation, in-depth interviews, and focus group discussions between July and October 2018. Overall, the ethnographic study utilised actors-centred frameworks (structuration theory and street-level bureaucracy). The study findings unravel the complexities involving HSAs' agency shaped by health system structures (staffing, infrastructure, drugs, and supplies) and informal structures (community relations, local power structures, gendered-household relations) which narrowed or widened their discretionary decision-making space. The flexibility of HSAs was a distinctive feature in their work, but they developed other coping mechanisms: task shifting, teamwork, creative community engagement, and referrals to deliver integrated maternal and child health services. HSAs' unique position as community-based providers meant they needed to consider diverse factors that constrained or facilitated their work. Overall, we argue that HSAs need to be fully involved in the design of community-level integrated health programmes. There should be a consideration to address both informal and formal structures that together shape agency. Additionally, CHWs' flexibility and agency to make locally informed decisions must be protected and maintained because it enhances their ability to deliver essential health services.