Aberrant activation of ERK signaling is a hallmark of lung cancer. Although constitutively activating mutations of EGFR and KRAS contribute to the hyperactivation of ERK1/2, other mechanisms remain elusive. In this study, the zinc finger protein ZNF251 was found to be upregulated in clinical lung cancer samples, and it promoted the growth of lung cancer cells and the growth of primary lung KPC cells from mouse models (Ad‐Cre, KrasG12D, and P53f/f). In studying the molecular mechanism, ZNF251 was found to inhibit the expression of dual‐specificity phosphatase 6, a negative regulator of ERK activation, by directly binding to its promoter region. Taken together, our data indicate the tumor‐promoting effects of ZNF251 in lung cancer and suggest that ZNF251 is a therapeutic target. ZNF251 promotes lung cancer by activating ERK signaling.