Introduction: Biomedical HIV prevention tools are available in France to prevent new infections. However, evidence suggests a lack of knowledge of these tools among sub-Saharan African immigrants, who are particularly affected by HIV due to social hardship, an indirect factor of HIV acquisition. We analysed the impact of an empowerment-based intervention on the knowledge of treatment as prevention (TasP), pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) in a population of precarious sub-Saharan African immigrants. Methods: Data were collected throughout the MAKASI project. Following an outreach approach, participants were recruited in public places based on their precarious situations and followed for six months (0, 3, 6 months) between 2018 and 2021. Participants were randomized into two groups and received an empowerment intervention sequentially (stepped wedge design). We used random-effects logistic regression models to evaluate the intervention effect on the knowledge of biomedical HIV prevention tools. ClinicalTrials.gov Identifier: NCT04468724. Results: The majority of the participants were men (77.5%), and almost half of them had arrived in France within 2 years prior to inclusion (49.3%). At baseline, 56% of participants knew about TasP, 6% knew about PEP and 4% knew about PrEP. Receiving the intervention increased the odds of knowing about PEP (aOR = 2.02 [1.09-3.75]; p < 0.026). Intervention effects were observed for TasP and PrEP only after 6 months. We found significant time effects for PEP (at 3 months, aOR = 4.26 [2.33-7.80]; p < 0.001; at 6 months, aOR = 18.28 [7.39-45.24]; p < 0.001) and PrEP (at 3 months, aOR = 4.02 [2.10-7.72]; p < 0.001; at 6 months, aOR = 28.33 [11.16-71.91]; p < 0.001). Conclusions: We showed that the intervention increased the knowledge of biomedical HIV prevention tools. The effect of the intervention was coupled with an important time effect. This suggested that exposure to the intervention together with other sources of information contributed to increased knowledge of biomedical HIV prevention tools among precarious sub-Saharan African immigrants.