The BCL-2 inhibitor venetoclax has transformed outcomes for older or frail patients with acute myeloid leukemia (AML), and its resistance mechanisms are becoming better defined, including compensatory and lineage-associated switches toward MCL-1 or BCL-xL dependence, oncogenic signaling activation, blast phenotype, and differentiation stage. Additional putative mechanisms-such as emerging BAX mutations, mitochondrial structure remodeling, integrated stress response, and metabolic adaptations, including enhanced amino acid uptake and fatty acid oxidation to sustain oxidative phosphorylation-require further validation.