Marine microbes are gaining attention among researchers for their polyextremophilic nature and ability to produce novel secondary metabolites. The coastal wetlands are widely investigated for their accessibility, leaving the islands, deep-sea, and other poly-extremophilic sites untouched. This study unveils marine actinobacteria and their biosynthetic gene clusters from the polyextremophilic island ecosystem. Thirty-eight polyextremophilic marine actinobacterial strains of 12 genera were isolated from 6 sediment samples collected around Vhan Island, India. Streptomyces sp. (39 %) was found predominantly, followed by; Micrococcus sp. (13 %), Rhodococcus sp. (10 %), Actinomyces sp. (8 %), Nesterenkonia sp. (5 %), Nocardia sp. (5 %), Brevibacterium sp. (5 %), Verrucosispora sp. (3 %), Actinoplanes sp. (3 %), Corynebacterium sp. (3 %), Jishengella sp. (3 %), and Microbispora sp. (3 %). Together twenty-two strains showed the presence of Polyketide Synthase-I (PKS-I) (13 strains), Polyketide Synthase-II (PKS-II) (18 strains), and Non-Ribosomal Peptide Synthetases (NRPSs) (10 strains). In addition, combinatorial gene clusters PKS-I + PKS-II (9 strains), PKS-II + NRPS (8 strains), and PKS-I + II + NRPS (3 strains) were also detected. Further, the Gas Chromatography and Mass Spectrometry (GC–MS) and Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS) analysis for the selected strains demonstrated their ability to produce diverse secondary metabolites with potential therapeutic and industrial values. In correlation, the antimicrobial studies also revealed that the isolated microbes could significantly inhibit the tested marine pathogens' growth. Further, all the gene clusters were stored as gene libraries for further usage. This study is one of its kind in exploring the extreme ecological niches and unveiling the diversity of rare and polyextremophilic marine actinomycetes from the Island ecosystem with its biosynthetic gene cluster potential.