Abstract Marbling, or intramuscular fat, is an important factor in meat quality. As a key regulator of lipid metabolism, AMP activated protein kinase (AMPK) may be associated with intramuscular fat accumulation. Our objective was to evaluate the relationship among AMPK and its associated signaling mediators, with marbling and lean growth in beef cattle. Steers with high intramuscular fat content (High IMF, 5.71 ± 0.36%, n = 5) and low intramuscular fat content (Low IMF, 2.09 ± 0.19%, n = 5) were selected. High IMF was associated with increased tenderness ( P < 0.05) and backfat thickness ( P < 0.01). Muscle weights were higher in Low compared to High IMF ( P < 0.05). High IMF steers had a reduced AMPK activity ( P < 0.01), reduced acetyl-CoA carboxylase phosphorylation ( P < 0.05), and reduced total mTOR ( P = 0.02) content. Data provide evidence that AMPK is involved in IMF deposition in beef cattle.