AMP-activated protein kinase (AMPK) is a metabolic stress-sensing enzyme responsible for maintaining cellular energy homeostasis. Activation of AMPK by salicylate and the thienopyridone A-769662 is critically dependent on phosphorylation of Ser108 in the β1 regulatory subunit. We identified the autophagy initiator Unc-51-like kinase 1 (ULK1) as a β1-Ser108 kinase. ULK1 phosphorylation was specific to the β1-isoform and sensitised AMPK to salicylate and A-769662. To investigate the cellular fate of β1-Ser108 phosphorylation, we performed a stable isotope dimethyl labelling-based quantitative proteomic and phosphoproteomic analysis using lentivirus-transduced S108A and S108E mutants of β1 in β1/2-dKO iMEFs cells. Following 1 h phenformin (2 mM) treatment, β1-S108A and β1-S108E transduced iMEF lysates were compared to trace out the changes in proteome and phosphoprotome to decipher the possible cellular role of β1-Ser108 phosphorylation.