Capsicum annum L. (sweet pepper) is a vegetable which belongs to Solanaceae family. In order to increase sustainable sweet pepper production, study was conducted on effect of natural fertilizers on its productivity under Sudano-Guinean climate of Adamawa Cameroon. Randomized complete block design with 07 treatments and 03 replications was used. Treatments that applied per plant were: compost (CBV); 20 g of vivianite (V20); 30 g of vivianite (V30); CBV and V20 mixture (CBV + V20); CBV and V30 mixture (CBV + V30); chemical fertilizer (T+) and unfertilized plants (T-). Stage of plants development; growth and yield as well as fruits physicochemical characteristics were evaluated. Results showed that flowering and fruiting of treated plants by natural fertilizers (compost and vivianite) were early compared to T- and T+ plants. Fruits yield from mixture of 1 kg of compost + 20 g of vivianite was significantly (p˂0.05) higher than that from the other treatments and is 1.46 fold higher than that from T+ plants. Overall, fruits from treated plants by natural fertilizers are richer in vitamin C and mineral elements than those from T- and T+ plants. Fruits vitamin C content from amended compost plants is 1.60 fold higher than that from T+ plants. These results suggest that the quality of natural fertilizer is important not only for improving sweet pepper growth and fruits yield, but also for improving nutritional value of fruits. 1 kg of compost + 20 g of vivianite mixture is recommended to sweet pepper grower of Adamawa Cameroon.