Citrus producers suffer significant losses caused by postharvest diseases, among which green mold, caused by the phytopathogenic fungus Penicillium digitatum, is particularly prominent. The intensive use of synthetic fungicides has led to the emergence of resistant phytopathogens and potentially negative consequences for the environment. In an effort to minimize their use without compromising the quality and quantity of citrus yields, producers are increasingly encouraged to adopt alternative approaches and integrated systems for controlling postharvest diseases. Bacteria of the genus Pseudomonas exhibit great potential for biological protection of agricultural products against phytopathogens. Given their proven effectiveness in suppressing some economically important pathogens, certain species and strains of Pseudomonas sp. are commercially available as microbiological formulations. The aim of this study is to examine the antifungal activity of fifteen autochthonous strains of Pseudomonas sp. isolated from a cave and a rhizosphere of lettuce using dual culture method against the most important postharvest pathogen of citrus fruits, Penicillium digitatum. Overall, 46.7% of the autochthonous Pseudomonas sp. strains show complete (26.7%) or pronounced (20.0%) inhibititon of the P. digitatum growth, with radial growth inhibition ranging from 47.4 ± 0.0% to 100.0 ± 0.0%. Furthermore, 40.0% of the strains exhibited weak inhibition (radial growth inhibition from 2.9 ± 4.2% to 32.6 ± 3.7%), while 13.3% of the strains had no effect at all on the growth of P. digitatum. The strains 2020_W2-8, 2022_01_SL2-11, 2022_01_SL2-17, and 2022_01_SMS-16 isolated from a cave completely inhibited fungal growth and proved to be the most effective, making them excellent potential candidates for use in biological formulations for the control and suppression of the phytopathogenic fungus P. digitatum.