Lung cancer is still the leading cause of death by cancer worldwide despite advances both in its detection and therapy. Multiple oncogenic driver alterations have been discovered, opening the prospective for new potential therapeutic targets. Among them, KRAS mutations represent the most frequent oncogene aberrations in non-small cell lung cancer (NSCLC) patients with a negative prognostic impact, but effective therapies targeting KRAS are not well characterized yet. Here, we demonstrate that the microRNA miR-34c-3p is a positive prognostic factor in KRAS-mutated NSCLC patients. Firstly, looking at the TGCA dataset, we found that high miR-34c-3p expression correlated with longer survival of KRAS-mutated NSCLC patients. In vitro assays on immortalized and patient-derived primary NSCLC cells revealed that miR-34c-3p overexpression increased apoptosis and lowered proliferation rate in KRASmut cells. Computational analysis and in vitro assays identified CDK1, one of the most promising lethal targets for KRAS-mutant cancer, as a target of miR-34c-3p. Moreover, the combination of CDK1 inhibition (mediated by RO3306) and miR-34c-3p overexpression resulted in an additive effect on the viability of KRASmut-expressing cells. Altogether, our findings demonstrate that miR-34c-3p is a novel biomarker that may allow tailored treatment for KRAS-mutated NSCLC patients.