The perpetual increase in the resistance offered by biofilm-forming nosocomial pathogens has become a critical clinical challenge. Marine Streptomyces sps present a promising future of novel compounds with novel applications. We focus on the anti-biofilm activity of marine Streptomyces against two major nosocomial pathogens from clinical samples, Pseudomonas aeruginosa and Staphylococcus aureus. Herein, Streptomyces griseoincarnatus, a species known to harbour alkaline protease inhibitors and anti-tumour compounds were found to exhibit anti-biofilm activity. The study progresses to decipher the anti-biofilm potential of the extract as 82.657 ± 1.1002% against P. aeruginosa and 78.973 ± 1.672% against S. aureus at 100 μg/mL. The strain under study, S. griseoincarnatus HK 12 (accession no MF100857) has revealed the presence of certain fatty acyl compounds namely, 13Z-Octadecenal, 9Z-Octadecenal, Arachidic acid, Tetracosanoic acid and Erucic acid by GC-MS screening. Furthermore, the active compounds were docked against the quorum sensing system, LasI. The compound 13Z-Octadecenal was found to bind to the conserved sites of substrate binding with a binding energy of -1.90 kcal/mol thus, affirming the inhibitory activity of the fatty acyl compound. These active compounds were previously reported to be a part of active extracts exhibiting relevant antagonistic activities, but this so far is the first time they are found possessing anti-biofilm activity. Interestingly, the toxicity level of the extract at a high concentration of 500 μg/mL is as low as 11.5% when tested against human lung cancer lines, A549. Thus the report highlights the evidence of the potential of S griseoincarnatus HK12 to be an active and safe anti-biofilm agent.