This study aimed at isolating microorganisms associated with the mesopelagic jellyfish Periphylla periphylla collected in Irminger Sea at a depth of 325 m in July 2020. Three different solid cultivation media; Hastings, Marine agar and Wickerham media were used for the isolation of the associated microorganisms. A total of 43 bacteria were isolated from the inner and outer surfaces of the umbrella of P. periphylla, but unfortunately, no fungal strain was isolated. Isolates were further identified by Sanger sequencing of the 16S rRNA gene, and based on phylogenetic distinctiveness (differences in closest relative species according to the nucleotide BLAST), 16 bacteria belonging to 8 different genera were selected and subjected to an OSMAC cultivation regime approach using liquid and solid marine broth and glucose– yeast–malt media. After 7 days of cultivation, cultures were extracted with ethyl acetate and assessed for antimicrobial activity against fish and human pathogens. Based on antimicrobial activity assessment, four most bioactive strains; Polaribacter sp. SU124, Shewanella sp. SU126, Psychrobacter sp. SU143 and Psychrobacter sp. SU137, were prioritized for a comparative and untargeted metabolomics analysis using feature-based molecular networking. These findings highlight the biotechnological potential of P. periphylla-associated microbiota.