This study was conducted to investigate adipokine [Apelin and brain-derived neurotrophic factor (BDNF)] and cardiac troponin (cTnI) response that emerged after adding an essential oil mixture (EOM) (Eucalytus glabutus labii, Thymus vulgaris, Cymbopogon nardus, and Syzygium aromaticum) at different rates to the drinking water of broilers in which thyroid dysfunction (hypo- and hyperthyroidism) had been experimentally induced. In the present study, 150 1-day-old Ross-308 male broiler chicks were used. They were divided into five groups, each with 30 animals. The groups were designed to include five subgroups: control (C). hypothyroid, hypothyroid + 250 ppm EOM, hyperthyroid, and hyperthyroid + 250 ppm EOM, with six animals in each group. At the end of the experiment, Apelin, p-BDNF, cTnI, T3, T4, and thyroid-stimulating hormone (TSH) levels were investigated in blood serum samples obtained by cervical dislocation from four randomly selected animals from each subgroup, making 100 animals in total. It was found that EOM administration resulted in a dose-dependent increase in p-BDNF and apelin levels. and a decrease in T4 levels in the experimentally induced hypo- and hyper-thyroidism groups, but did not affect T3 and cTnI levels. Conversely, an increase in TSH level was observed in the hypothyroidism groups, whereas a decrease was observed in groups with hyperthyroidism. This study is the first to examine adipokine (Apelin and BDNF) and aid response to EOM administration in thyroid dysfunction.