The immune system plays a crucial role in defending the body against foreign invaders, and the balance of various polyunsaturated fatty acids, such as alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), can impact immune cell functions and overall immune responses. This study aimed to assess the effectiveness of mussel oil extracts in modulating inflammatory responses by analysing their effects on immune cell lines and cytokine expression. Four different mussel oil extracts were obtained using two extraction methods (organic solvent and supercritical CO2 extraction) from two tissue sources (fresh and commercial). These extracts were then tested at various concentrations on T lymphocyte (Jurkat) cells, monocytes, and macrophages (THP-1 and U-937). Cytokine levels were quantified using ELISA. The results showed that the solvent-extracted samples had a dose-dependent effect on tumour necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) cytokine secretion in THP-1 and U937 cells, with the extract from a commercial mussel powder being more efficient than the extract from fresh powder. However, supercritical CO2 samples showed elevated cytokine secretion levels despite their high omega-3 content. Furthermore, 100 ug/mL extract from fresh powder successfully reduced interleukin-2 (IL-2) secretion while maintaining cell viability after stimulation. The study demonstrated that solvent-extracted mussel oil can effectively regulate cytokine secretion, modulate immune cell activation, and alleviate inflammation. These findings offer valuable insights into using mussel oil extracts to treat inflammatory disorders and enhance immune responses.