The study evaluated the effect of peer-led education intervention on predisposing factors of occupational risk prevention practices among medical waste handlers in South west, Nigeria. The specific objectives were to determine the baseline assessment of the predisposing factors of occupational risk prevention among the participants; and assess the effect of peer- led educational intervention on the predisposing factors in occupational risk prevention at 12th week post intervention follow up among the participants. The study was an interventional study and adopted a two group quasi-experimental design (one experimental group and one control group). Participants of the study were the hospital attendants that served as medical waste handlers working at Olabisi Onabanjo University Teaching Hospital, Sagamu and Federal Medical Centre, Ebute Meta, Lagos. A structured questionnaire was used for data collection to determine the baseline assessment and outcome evaluation of the intervention. Data collected were analysed using descriptive and inferential statistics. The finding revealed that at 12th week post intervention for control and experimental groups, the mean score knowledge of risk prevention for control group is 11.88±4.72 while the experimental group is 17.02±5.02 with mean difference of 5.14; perception mean score of risk prevention for control group is 10.54±3.47 while experimental group is 18.02±5.27 with mean difference of 7.48; and mean score of attitudinal dispositions of risk prevention for control group is 13.26±3.05 while the experimental group is 19.74±4.09. The study concludes that peer led educational intervention programs was effective in improving the knowledge of risk prevention, perception of risk prevention, attitudinal dispositions of risk prevention, reinforcing factors on risk prevention, and enabling factors on risk prevention practices among the medical waste handlers. It was recommended among others that there should be orientation, induction program for new employees, with regular and continuous training for the medical waste handlers. Keywords: Peer-Led Education, Predisposing Factors, Occupational Risk, Prevention Practices, Medical Waste Handlers,