In soybean (Glycine max) cultivation, the disease pathogen causing Sclerotinia stem rot (SR) disease is Sclerotinia sclerotiorum (Lib.) de Bary. The Sclerotinia sclerotiorum causes significant crop losses due to its seed and soil borne infecton. In this study, the effectiveness of biological control agents such as Coniothyrium minitans (CM), Trichoderma harzianum (TH), and Bacillus subtilis (BS), which can be used as alternatives to chemical control in managing SR, was investigated when applied together and at 10-day intervals. In the study, the lowest infected plant rates in biological control with SR were obtained from biological agent applications 10 days before disease inoculation. In this context, the lowest disease severity % and the highest % effect rate were obtained from the CM+10 days later SR application with 31.68% and 61.94%, followed by BS+10 days later SR and TH+10 days later SR, respectively. All biological agents have been found to significantly reduce disease occurrence compared to control. In the study, the most successful biological agent alternative to chemical control against Sclerotinia sclerotiorum was Coniothyrium minitans, followed by Bacillus subtilis and Trichoderma harzianum, respectively. The study results revealed that the applications of biological preparations before, during, or after fungal infection is an important factor in improving control of the disease pathogen.