The volatile oils of flowers (TFE), leaves (TLE) and stems (TSE) of Tripleurospermum conoclinium (Boiss. & Balansa) Hayek were obtained by hydrodistillation method for 3 hours with Clevenger‐type apparatus. Chemical composition of oils was determined by GC‐MS analyses. Antidiabetic, anti‐inflammatory and antioxidant activities of oils were tested by α‐glucosidase inhibitory, 5‐lipoxygenase inhibitory and DPPH/ABTS radical scavenging methods, respectively. Eighty‐five constituents were identified in flower oil (78.3%). The major compounds of flower oil were artemisia ketone (10.5%), β‐oplopenone (6.0%), tricosane (4.5%), terpinen‐4‐ol (3.7%) and artemisia alcohol (3.5%). Sixty‐two constituents were identified in leaf oil (67.0%). 1‐octadecanol (11.5%), caryophyllene oxide (5.7%), elemol (3.9%), phytol (3.5%), ledene oxide (3.3%) and artemisia ketone (3.1%) were found as main constituents in the leaf oil. Forty‐six constituents were determined in the stem oil (75.1%). The main compounds of the stem oil were 1‐octadecanol (11.1%), β‐oplopenone (5.5%), ledene oxide (5.5%), caryophyllene oxide (4.4%) and phytol (3.0%). TLE and TSE displayed strong antidiabetic activity with IC50 values of 21.30 and 29.57 µg/mL against α‐glucosidase enzyme, respectively. TLE showed the best anti‐inflammatory activity with an IC50 value of 91.02 µg/mL while TFE and TSE exhibited moderate activity with IC50 values of 186.50 and 257.10 µg/mL, respectively. TFE and TLE were found to possess moderate antioxidant activity with IC50 values of 572.80 and 385.80 µg/mL against ABTS radical while all essential oils showed weak activity against DPPH radical. To the best of our knowledge, this is first report on chemical composition and biological activities of T conoclinium essential oils.