Escherichia coli O157:H7 continues to be one of the major foodborne pathogens causing a global public health concern. Effective control of E. coli O157:H7 in foods is crucial for improving food safety and public health. This study was to evaluate the potential of a recently isolated phage Φ241 as a biocontrol agent against E. coli O157:H7 in model food systems (cucumber juice, cucumber juice supplemented with salt, and beef broth). A filter-sterilized food was inoculated with E. coli O157:H7 to achieve an initial cell concentration of 1.2E+06 CFU/mL and with an appropriate amount of phage stock to achieve a target MOI (1, 10, or 100). The inoculated food was incubated at 37°C for 10 h. Samples were taken hourly and analyzed using the plate count method and the plaque assay. In the absence of phage, E. coli O157:H7 grew very well in both cucumber juice and beef broth. The cell concentration increased exponentially during the first 4-hr incubation and reached 2.0E+08 CFU/mL within 6 hr. In the presence of phage Φ241, cell lysis occurred rapidly in cucumber juice, resulting in at least 4-log reduction in cell concentration within 3 hrs regardless of MOI. As a result, the bacterial concentrations were more than 5 log units lower than that of the control. Similar results were also obtained in cucumber juice supplemented with 1 to 2 % NaCl at MOI 10. Phage infection in beef broth at MOIs 1, 10, and 100 caused 2.3-, 3.7-, and 3.3-log reduction in cell concentration within 4 hrs, respectively. These results showed that the infection by phage Φ241 effectively controlled E. coli O157:H7 in the model food systems, suggesting that phage Φ241 has a high potential and a wide range of application as a biocontrol agent of E. coli O157:H7 in various foods.