In Burkina Faso, street food vendors are key in ensuring food safety in urban markets, particularly within the poultry value chain. The sale of high-risk ready-to-eat chicken by these vendors poses substantial health hazards, emphasizing the urgency for capacity-building to enhance food safety practices. This study evaluated the effect of a participatory interactive three-day training program coupled with tool supply on self-reported and observed behavior, and knowledge, attitudes, and cognitions of vendors of ready-to-eat chicken meat in Ouagadougou's informal markets. A two-armed RCT was conducted, including pre- and post-training vendor surveys, along with direct outlet observations. Total sample size comprised 162 vendors, with 72 in the treatment group and 90 in the control group. Self-reported behavior - measured on a five-point scale - significantly improved in the treatment group including higher frequency of mask wearing (1.8 ± 0.8 vs 2.5 ± 1.2, p < 0.001) and inspecting nail hygiene (4.3 ± 0.8 vs. 4.7 ± 0.6, p < 0.001). Treatment outlets improved on securing adequate evisceration platforms (1.3 ± 0.6 vs. 1.0 ± 0.5, p = 0.054), regular carcass water renewal (61.8% vs. 36.4%, p = 0.038), and handwashing during carcass management (1.1 ± 0.5 vs. 0.9 ± 0.3, p = 0.008). Better adherence to handwashing (1.1 ± 0.4 vs. 0.9 ± 0.3, p = 0.051), fork use (58.9% vs. 41.8%, p = 0.029), proper handwashing facilities (38.4% vs. 20.9%, p = 0.014), and waste management (64.4% vs. 37.8%, p < 0.001) were observed in treatment outlets. Trained vendors scored significantly higher than controls on knowledge (effect size 0.75, p < 0.001). Vendors rated the perceived usefulness and perceived ease of use, trust in materials/tools - measured on a five-point scale - as high, and perceived mean increased daily profits (21,242 FCFA) and number of customers (8.3) following training. In conclusion, training combined with a tool package proved effective in fostering significant food safety behavior changes, underscoring its substantial impact beyond just knowledge enhancement. For lasting behavior changes, ongoing training and support, an enabling environment, and strong incentives that prioritize vendor food safety behaviors in informal markets are crucial. •Impact of a food safety training and tool package for chicken vendors in Ouagadougou.•A two-arm RCT combined surveys with observations with measurements 6 months apart.•Training and tools improved and enabled self-reported and observed behavior.•Trainings significantly raised vendors' food safety knowledge.•Perceived benefits of training included increased profits and number of customers.