Abstract: Bacterial strains of the genus Pseudoalteromonas, which includes 48 species, are widely distributed in various ocean environments. Many strains are often abundant and the highest protease producer among marine culturable protease-secreting bacteria, suggesting their important role in marine organic nitrogen degradation and cycling. The extracellular proteases of Pseudoalteromonas are diverse, including serine proteases, metalloproteases, and cystine proteases. Pseudoalteromonas proteases have unique properties, such as cold adaptation, salt tolerance, distinct substrate specificity, and catalytic mechanism. They play important ecological roles in marine organic nitrogen degradation and in the interactions of Pseudoalteromonas with other organisms. Some Pseudoalteromonas proteases have shown promising application potentials in bioactive peptide preparation and meat processing. In this review, advances in our knowledge of Pseudoalteromonas proteases are introduced, with a focus on diversity, characters, ecological significance, and application potentials.