Background There is still no clinically approved agent for mutant KRAS, which is the most common alteration in non-small-cell lung cancer (NSCLC). Flavopiridol is a semisynthetic flavonoid that inhibits cell growth through cyclin-dependent kinases in G1/S or G2/M of the cell cycle and induces apoptosis. In this study, we evaluated its effect on cellular apoptosis, survival, and metastasis mechanisms on KRAS mutant A549, Calu-1, and H2009 cell lines. Methods The cytotoxic effects of flavopiridol on NSCLC cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell viability test. The cells were treated with 200 and 400 nM flavopiridol, and, then, apoptosis, survival, and metastasis-related protein expressions were determined by Western blot analysis. The antimetastatic effects of flavopiridol were assessed by wound healing and Galectin-3 activity assay. Results Flavopiridol drastically affected toxicity in all KRAS mutant NSCLC cells at nanomolar concentrations. Also, it could efficiently inhibit wound healing and Galectin-3 activity in all the cells tested. However, the metastasis-related protein expressions did not reflect these obvious effects on blotting. p-Erk was activated as a cellular survival mechanism to escape apoptosis in all the cells tested. Conclusion Although there are many mechanisms that still need to be elucidated, flavopiridol can be used as a metastasis inhibitor and an apoptosis inducer in KRAS mutant NSCLC.