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<i>Xanthomonas arboricola</i> pv. <i>juglandis</i> (hereafter <i>X. juglandis</i>) is the etiological agent of walnut blight, the most important bacterial disease affecting walnut production worldwide. Currently, the disease is treated mainly with copper-derived compounds (e.g., CuSO₄) despite the evidence of genetic resistance in these strains. Regarding the effectiveness and sustainability, the use of a bacteriophage appears to be a biocontrol alternative to reduce <i>X. juglandis</i> load and symptomatology of walnut blight. Here, the phages <i>f</i>20-Xaj, <i>f</i>29-Xaj, and <i>f</i>30-Xaj were characterized, and their effectiveness in walnut orchards against walnut blight was determined. These bacteriophages showed a specific lytic infection in <i>X. juglandis</i> strains isolated from Chile and France. Phylogenetic analysis of the complete genome of <i>f</i>20-Xaj and <i>f</i>30-Xaj indicates that these phages belong to the <i>Pradovirus</i> genus. In the field, the cocktail of these bacteriophages showed similar effectivity to CuSO₄ in the reduction of incidence and severity in walnut tissue. Moreover, the bacterial load of <i>X. juglandis</i> was significantly reduced in the presence of bacteriophages in contrast to a CuSO₄ treatment. These results show that the use of bacteriophages can be an alternative to combat the symptoms of walnut blight caused by <i>X. juglandis</i>.