Potentilla fulgens is known as Himalayan Cinquefoil and Lyngniangbru, rich in polyphenolic constituents and used as folk medicine by inhabitants of northeast India. This study intended to develop and validate a high‐performance thin‐layer chromatography method for the quantification of catechin in the Potentilla fulgens roots extract and explore its antioxidant potential, acetylcholinesterase, and hydroxymethylglutaryl‐coenzyme A reductase inhibition activity. The separation was achieved using the mobile phase of toluene: ethyl acetate: acetone: formic acid (6:6:6:1, v/v) in which the Potentilla fulgens roots extract delivered a condensed peak at RF 0.58 equivalent to catechin as a phytomarker. The amount of catechin in the Potentilla fulgens roots extract was found to be 2.01% w/w. Potentilla fulgens roots extract showed abundant 1,1‐diphenyl‐2‐picrylhydrazyl scavenging potential with half‐maximal inhibitory concentration values of 43.39 ± 1.43 μg/ml and inhibited acetylcholinesterase and hydroxymethylglutaryl‐coenzyme A reductase in a concentration‐dependent manner against (half‐maximal inhibitory concentration 74.78 ± 1.2 and 64.02 ± 1.7 μg/ml, respectively). The developed and validated high‐performance thin‐layer chromatography method is easy, accurate, and appropriate. These results support the use of Potentilla fulgens as folk medicine and suggest that Potentilla fulgens might be utilized as a rich source of natural antioxidants as well as acetylcholinesterase and hydroxymethylglutaryl‐coenzyme A reductase enzyme inhibitory agents.