Blumea laciniata (Roxb.) DC. is a folk medicinal annual herb of the Asteraceae family that grows in South and Southeast Asia. In order to evaluate its phytopharmaceutical potential against diabetic, obesity, and Alzheimer’s, a comprehensive phytochemical profile, in vitro and in silico enzyme inhibitory activity against α-amylase, α-glucosidase, lipase, cholinesterases, and tyrosinase along with in vitro antioxidant activity were performed. Additionally, in vivo antidiabetic activity and acute toxicity were also evaluated. The total phenolic content in various organs follows the following order: old leaf > flower bud > young leaf > flower > young stem > old stem > root, while total flavonoids followed the order: flower bud > old leaf > young leaf > flower > young stem > old stem > root. The identified phenolic compounds are 3,4-dihydroxybenzoic acid, caffeic acid, vanillic acid, p-coumaric acid, syringic acid, rosmarinic acid, trans-cinnamic acid, catechin, catechol, (-) epicatechin, rutin, quercetin, myricetin, and kaempferol, which are also expressed differently in various organs. Solvent extracts demonstrated strong antioxidant activity as well as varying levels of inhibition against the enzymes tested, with strong inhibitory activity against α-amylase, α-glucosidase, and lipase. Thirteen phenolic compounds displayed strong binding affinity in silico against studied enzymes, thus documented as bioactive. Furthermore, solvent extracts significantly suppressed blood glucose levels in mice with induced diabetes and extracts were not acutely toxic. The results suggest that Blumea laciniata (Roxb.) DC. could be a potential candidate for developing new phytopharmaceuticals and bioactive ingredients.