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OMVs and Violacein-loaded OMVs were isolated, characterized, and used in the treatment of murine melanoma. Violacein-loaded OMVs decreased melanoma cell viability and delivered violacein into the cytosol of these cells. In addition, the treatment of tumor-bearing mice with OMVs and non-violacein-loaded OMVs was associated with tumor regression. The antitumor response was associated with the accumulation of M1-type macrophages into the tumor and the mRNA overexpression of antitumor mediators. Our results suggest that OMVs can be nanocarriers of highly hydrophobic agents and induce antitumor responses to eliminate tumors.