The aim of this study was to investigate the essential oil (EO) compositions and antioxidant activities from petals of three wild tree peony species (Paeonia delavayi, P. lutea, and P. rockii) and eleven P. suffruticosa cultivars from different cultivar groups. The EOs yields varied from 0.63% to 1.25% (v/v) among samples when using supercritical CO2 extraction. One hundred and sixty-three components were detected by GC/MS; and among them, linalool oxide, (Z)-5-dodecen-1-yl acetate, nonadecane, (Z)-5-nonadecene, heneicosane, phytol, and linoleic acid ethyl ester were dominant. According to hierarchical cluster analysis, principal component analysis and correspondence analysis, P. lutea, P. delavayi, and 'High Noon' were clustered in a group described as having a refreshing herbal-like note due to high rates of phytol and linalool oxide. Notably, P. lutea and P. delavayi also had strong DPPH and ABTS radical scavenging activities. These results suggest that P. lutea and P. delavayi are the most promising candidates as useful sources of fragrances and natural antioxidants.