Marine bioprospecting, which involves the exploration of genetic and biochemical material from marine organisms, can be used towards addressing a broad range of public and environmental health applications such as disease treatment, diagnostics and bioremediation. Marine genetic resources are important reservoirs for such bioprospecting efforts; however, the extent to which they are used commercially for natural product discovery and the marine sources from which they are derived are not well understood. Here we introduce a comprehensive database of marine genes referenced in patent filings, the Marine Bioprospecting Patent database. It includes 92,550 protein-coding sequences associated with 4,779 patent filings, identified by analysing all relevant records from genetic sequence databases. Three companies alone—BASF, IFF and DuPont—included sequences from 949 species (more than half of referenced species with identified marine origin). Microbial life in the deep sea, a vast and remote biome predominantly beyond national jurisdiction, is already attracting substantial economic interest; the top ten patent holders have all filed marine gene patents referencing sequences from deep-sea life. Our findings provide an updated understanding of the marine bioprospecting landscape, contribute to the sustainable use of marine biodiversity and underscore the need for policymakers to ensure stewardship of deep-sea ecosystems.