BACKGROUND: Meeting the sexual and reproductive health (SRH) needs of adolescents and young people (AYP) requires their meaningful engagement in intervention design. We describe an iterative process of engaging AYP to finalise the design of a community-based, peer-led and incentivised SRH intervention for AYP aged 15-24 in Lusaka and the lessons learnt. METHODS: Between November 2018 and March 2019, 18 focus group discussions, eight in-depth interviews and six observations were conducted to assess AYP's knowledge of HIV/SRH services, factors influencing AYP's sexual behaviour and elicit views on core elements of a proposed intervention, including: community-based spaces (hubs) for service delivery, type of service providers and incentivising service use through prevention points cards (PPC; "loyalty" cards to gain points for accessing services and redeem these for rewards). A total of 230 AYP (15 participated twice in different research activities) and 21 adults (only participated in the community mapping discussions) participated in the research. Participants were purposively selected based on age, sex, where they lived and their roles in the study communities. Data were analysed thematically. RESULTS: Alcohol and drug abuse, peer pressure, poverty, unemployment and limited recreation facilities influenced AYP's sexual behaviours. Adolescent boys and young men lacked knowledge of contraceptive services and all AYP of pre and post exposure prophylaxis for HIV prevention. AYP stated a preference for accessing services at "hubs" located in the community rather than the health facility. AYP considered the age, sex and training of the providers when choosing whom they were comfortable accessing services from. PPCs were acceptable among AYP despite the loyalty card concept being new to them. AYP suggested financial and school support, electronic devices, clothing and food supplies as rewards. CONCLUSIONS: Engaging AYP in the design of an SRH intervention was feasible, informative and considered responsive to their needs. Although AYP's suggestions were diverse, the iterative process of AYP engagement facilitated the design of an intervention that is informed by AYP and implementable. TRIAL REGISTRATION: This formative study informed the design of this trial: ClinicalTrials.gov, NCT04060420. Registered 19 August, 2019.