<p>This research aimed to isolate rhizospheric and endophytic actinobacteria from citrus orchards, and evaluate their potential for biological control of citrus pathogens <i>Alternaria alternata</i> and <i>Pseudomonas syringae</i> pv. <i>syringae</i>, as well as their effect on sour orange seeds (<i>Citrus aurantium</i> L.) germination in laboratory conditions. A total of 100 actinobacterial strains were isolated from the rhizosphere and aerial parts of citrus trees from southern and northern regions of Iran. Their bio-protective efficacy against the pathogens was investigated in dual-culture assays. Then, the ability to produce hydrolytic enzymes, growth promotion characteristics, and seed germination assay of selected isolates were evaluated. Twenty-five isolates substantially inhibited the growth of pathogenic fungi, with 11 isolates exhibiting inhibition rates exceeding 80%. Five isolates exhibited antibacterial activity, with the highest efficacy observed in isolates S17F and S4A. Although all 25 isolates produced ammonia, their abilities for N₂ fixation, phosphate solubilization, ACC-deaminase activity, siderophore production, indole acetic acid (IAA) synthesis, and hydrolytic enzyme production were different. Five isolates significantly increased the seed vigor of sour orange, of which S7 was the most effective. UHPLC analysis of culture filtrate from S4A isolate revealed the presence of pyrrole carboxamide and amicoumacin-related compounds. Finally, three most effective strains (S4A, S7, and S17F) demonstrating the highest antagonistic activity and PGP capability were analyzed phylogenetically. Analysis of <i>rpoB</i> and 16&#xa0;S rRNA genes of these isolates confirmed that they were closely related to <i>Streptomyces</i> spp. These findings underscore the potential of these isolated <i>Streptomyces</i> spp. as candidate for bio-control agents and biofertilizers for sustainable citrus orchard management.</p>