This study isolated and characterized a novel lytic bacteriophage, vB_EfKS5, targeting Enterococcus faecalis, an antibiotic-resistant foodborne pathogen capable of forming biofilms. The phage exhibited a broad host range, infecting 75.9% of E. faecalis isolates and 42.9% of E. faecium isolates, and efficiently disrupted established biofilms. Whole-genome sequencing revealed a 59,246-bp genome lacking lysogeny-, toxin-, and antibiotic resistance-related genes, supporting its safety for food applications. Furthermore, combining vB_EfKS5 with nisin produced a strong synergistic antibacterial effect in both broth and pasteurized milk, significantly reducing bacterial counts and delaying bacterial regrowth. These findings demonstrate that vB_EfKS5 is a promising biocontrol agent for improving food safety and extending the shelf life of food products.