More than 60% of nonsmall cell lung cancer (NSCLC) patients show a positive response to the first ALK inhibitor, crizotinib, which has been used as the standard treatment for newly diagnosed patients with ALK rearrangement. However, most patients inevitably develop crizotinib resistance due to acquired secondary mutations in the ALK kinase domain, such as the gatekeeper mutation L1196M and the most refractory mutation, G1202R. Here, we develop XMU‐MP‐5 as a new‐generation ALK inhibitor to overcome crizotinib resistance mutations, including L1196M and G1202R. XMU‐MP‐5 blocks ALK signaling pathways and inhibits the proliferation of cells harboring either wild‐type or mutant EML4‐ALK in vitro and suppresses tumor growth in xenograft mouse models in vivo. Structural analysis provides insights into the mode of action of XMU‐MP‐5. In addition, XMU‐MP‐5 induces significant regression of lung tumors in two genetically engineered mouse (GEM) models, further demonstrating its pharmacological efficacy and potential for clinical application. These preclinical data support XMU‐MP‐5 as a novel selective ALK inhibitor with high potency and selectivity. XMU‐MP‐5 holds great promise as a new therapeutic against clinically relevant secondary ALK mutations. Synopsis Despite the clinical success of ALK inhibitors in NSCLC, multiple drug‐resistant mutations in ALK are inevitably reported. XMU‐MP‐5 overcomes resistance to first and second generation ALK inhibitors in vitro and in vivo, thus holds great promise for the therapeutic use against ALK‐positive NSCLC. XMU‐MP‐5 is a new ALK inhibitor with high potency and selectivity. XMU‐MP‐5 overcomes acquired resistance to first and second generation ALK inhibitors, including ALKL1196M and ALKG1202R. XMU‐MP‐5 induces significant regression of lung tumors in ALK wild‐type and L1196M GEM models. Despite the clinical success of ALK inhibitors in NSCLC, multiple drug‐resistant mutations in ALK are inevitably reported. XMU‐MP‐5 overcomes resistance to first and second generation ALK inhibitors in vitro and in vivo, thus holds great promise for the therapeutic use against ALK‐positive NSCLC.