Few studies have explored land access, a structural driver of health, and women's participation in livelihood interventions to improve food security and HIV outcomes. This qualitative study, embedded within Shamba Maisha (NCT02815579)-a randomized controlled trial (RCT) examining the impact of a multisectoral intervention among farmers living with HIV in western Kenya-sought to explore the influence of perceived access to and control of land on agricultural productivity, investments, and benefits. Thirty in-depth interviews (IDIs) were conducted with purposively sampled men and women, 3 to 6 months after receiving intervention inputs; data were deductively and inductively coded and analyzed. Farming practices and participation in Shamba Maisha were dependent on land tenure and participants' perceived strength of claim over their land, with participants who perceived themselves to be land insecure less likely to make long-term agricultural investments. Land tenure was influenced by a number of factors and posed unique challenges for women which negatively impacted uptake and success in the intervention. Data underscore the importance of secure land tenure for the success of similar interventions, especially for women; future interventions should integrate land security programming for improved outcomes for all.