Organic materials, whose importance is increasing day by day in terms of soil fertility, plant nutrition, and sustainable agriculture in the world, need to be shown to be more effective against chemical fertilizers in order for farmers to adopt and use them more. The study was carried out to determine the effects of different organic fertilizer forms (farmyard manure (FM1 = 2500, FM2 = 5,104,000, FM3 = 7500, and FM4 = 10,000 kg ha−1), leonardite (L1 = 5000 and L2 = 10,000 kg ha−1) and vermicompost (V1 = 2500, V2 = 5000, V3 = 7500, and V4 = 10,000 kg ha−1)) on the yield components and some macro and micronutrient contents of the cowpea (Vigna unguiculata L.). The study, which was carried out under the Kahramanmaraş Mediterranean ecological conditions in 2020–2021, was conducted according to the experimental design of completely randomized blocks with three replications. As a result of the study, it was found that the differences between the fertilizer forms were significantly effective in terms of all the examined characteristics. It was determined that the seed yields varied between 3043.3–4126.7 kg ha−1, and according to the results of the two-year study, 10,000 kg ha−1 vermicompost would be sufficient to obtain the highest cowpea yield (4126.7 kg ha−1) under Mediterranean climate conditions.