Marine ecosystems are a rich source of bioactive natural products with remarkable therapeutic properties. Several marine-derived compounds—such as trabectedin, eribulin, bryostatin, ziconotide, and fucoidan—have demonstrated efficacy in treating cancer, infections, neurological disorders, and inflammation. As the interest in marine pharmacology expanded, the need to align drug development with ethical and religious frameworks becomes increasingly relevant, particularly in Muslim-majority contexts where Halal compliance is essential. This chapter explores the intersection of marine-based drug discovery and Halal pharmaceutical standards. It categorizes key marine organisms according to their Halal criticality—ranging from widely accepted sources like fish oils and algae to high-risk organisms such as pufferfish and cone snails. The discussion includes perspective from various Islamic schools of thought, highlighting jurisprudential differences in the permissibility of marine life. Additionally, the chapter emphasizes the significance of aquaculture, which supplies a substantial portion of marine-derived ingredients used in pharmaceuticals. It addresses the importance of feed composition, farming practices, and processing methods in relation to their impact on Halal integrity. Additionally, a structured framework for Halal evaluation in marine-based drug development is proposed, covering aspects such as source permissibility, processing agents, additives, contamination risk, environmental sustainability, spiritual compatibility, and certification procedures. By integrating pharmacological insight with Islamic bioethical principles, this chapter offers guidance for ensuring both therapeutic efficacy and Halal compliance. It promotes inclusive, ethically grounded drug development for a diverse global market.