Thirty-one endophytic streptomycete and non-streptomycete actinobacteria were extracted from healthy date palm root tissues. In vitro screening demonstrated that the antifungal efficacy of isolate #16 correlated with the synthesis of cell-wall disintegrating enzymes, while isolate #28 exhibited antifungal activity through diffusible metabolites, although also producing volatile antifungal chemicals. Based on 16S rRNA gene sequencing, isolates #16 and #28 were classified as Streptomyces polychromogenes UAE2 (Sp; GenBank Accession #: OK560620) and Streptomyces coeruleoprunus UAE1 (Sc; OK560621), respectively. The two antagonists were isolated from root tissues up to 12 weeks post-inoculation, effectively colonizing the root cortex and xylem vessels, suggesting that date palm roots provide an appropriate environment for these endophytic isolates. At the conclusion of the greenhouse trials, the onset of sudden decline syndrome (SDS) was significantly inhibited by 53% by the administration of Sp and by 86% with Sc, so validating their efficacy in disease management. The findings indicated that the estimated disease severity indices in affected seedlings were significantly (P<0.05) diminished from 4.75 (on a scale of 5) to 2.25 or 0.67 by either Sp or Sc, respectively. Moreover, the conidial counts of the pathogen decreased considerably (P<0.05) by 38% and 76% with Sp and Sc, respectively, in comparison to infected seedlings with F. solani (control). Consequently, the suppression of disease symptoms was more effective in seedlings pre-inoculated with S. coeruleoprunus, suggesting that the diffusible antifungal metabolites were accountable for the retardation of F. solani in these plants. This is the inaugural report of actinobacteria naturally present in date palm tissues functioning as microbial antagonists against SDS in date palm.