Proteus mirabilis is an opportunistic Gram-negative uropathogen responsible for a substantial number of catheter-associated urinary tract infections, especially in long-term catheterised patients. The globally increasing rates of antimicrobial resistance necessitate the search for new alternatives to antibiotics. Bacteriophages and phage-derived proteins, such as endolysins and depolymerases, have emerged as promising antimicrobial agents for the prevention, control, and treatment of bacterial infections. Several new Proteus bacteriophages were isolated, and it was demonstrated that phage particles can be immobilised on the surfaces of silicone urinary catheters treated with cold plasma, thereby creating an antimicrobial coating. It was further demonstrated that the anti-biofilm activity of a depolymerase-containing Proteus phage is enhanced by co-administration with cold-plasma-activated water, and that the synergistic effect of this combination is dependent on the order of treatment. Two Proteus endolysins and a depolymerase were identified and characterised, and the antibacterial properties of these enzymes were demonstrated. It was also shown that mortality in Galleria mellonella infected with Proteus could be reduced by the application of the purified depolymerase alone. Finally, a new machine-learning tool was developed to predict depolymerase genes in bacteriophage genomes.