Sensitivity of plants of the genus Capsicum to water deficiency is a great problem in the cultivation of sweet and hot pepper. It is becoming necessary to use plant irrigation during the growing season and to apply alternative methods that increase plant tolerance to water deficit. A large role in this regard is given to arbuscular mycorrhizal fungi (AMF) which contribute to enhanced water supply to plants by increasing the absorptive area of the root system. The effects of AMF inoculation and irrigation of plants of a native sweet pepper cultivar, ‘Roberta F1’, on fruit yield and yield structure as well as on fruiting dynamics were determined in a study conducted over the period 2016–2018 in an organic farm located in south-eastern Poland. The highest total and marketable yield as well as the largest number of pepper fruits produced were obtained for pepper cultivation with simultaneous AMF inoculation and irrigation throughout the entire growing season. Yield and number of pepper fruits were affected to a greater extent by AMF colonization than by plant irrigation. Inoculation of plants with AMF at the transplant stage also beneficially affected earliness of fruiting. Moreover, AMF inoculation and irrigation of plants significantly reduced the incidence of blossom-end rot (BER).