A simple and rapid electrochemical method was established to quantify the total polyphenol (TP) content and assess their antioxidant activity (AA) in roots of three Echinacea purpurea (E. purpurea) species using square wave voltammetry (SWV). Individual polyphenol components were identified, and then quantified by ultra‐high performance liquid chromatography coupled with mass spectrometery (UPLC‐MS). Two major polyphenols, chicoric (ChA) and caftaric (CFT) acids, were identified by mass spectroscopy in the extract of E. purpurea samples. The Accuracy of the proposed SWV electrochemical method for TP content and AA analysis was validated by the highly sensitive UPLC‐MS technique and standard ABTS method, respectively. A high correlation was noticed between the results, indicating the high sensitivity and reliability of the proposed SWV method for polyphenols analysis and AA evaluation in natural herbal samples.