NRAS activating mutations occur in 15-25% of melanoma patients. However, this subtype is more aggressive and refractory to current treatment modalities, including targeted MEK inhibitors, immunotherapies, and the recently emerging RAS inhibitors. Accordingly, identifying novel therapeutic targets and designing novel antimelanoma strategies is of utmost clinical relevance. Melanomas often harbor hyperactive nitric oxide synthases (NOS) which correlates strongly with poor prognosis. NOS is also known to be activated by ERK signaling. The nitric oxide so produced, induces nitrosylation, a post-translational modification, which dysregulates various kinases and phosphatases. We sensitized NRAS-mutant melanomas to targeted MEK inhibitors by inhibiting nitrosylation. This outcome revealed a strong correlation between global de-nitrosylation and downregulation of MEK-ERK cascade with a concomitant de-nitrosylation of NRAS and other small GTPases like Rho and Rac, dual specificity phosphatases, and ribosomal S6 kinase. In vivo, we observed extreme regression of NRAS-mutant melanoma tumors generated in an immunocompetent mouse model in response to a sequential nitrosylation inhibition and MEK inhibition. In addition to MEK-ERK downregulation, this strategy activated the CD8+ T cells in the tumor microenvironment. We conclude that while nitrosylation hyperactivates the RAS-RAF-MEK-ERK cascade, it also suppresses anti-melanoma immune response, bolstering progression and MEKi resistance. The underlying mechanism(s) will be crucial in identifying novel therapeutic vulnerabilities against aggressive, currently incurable NRAS-mutant melanomas with potential clinical application in other melanoma subtypes.