Oliveria decumbens Vent. is an aromatic, endemic plant from southern Iran renowned for its numerous health benefits. This study identified fatty acids in eight O. decumbens ecotypes and assessed their antioxidant and amylase activities. Flowers of eight ecotypes of the O. decumbens plant were collected from three provinces of Iran and fatty acids were extracted by in-vitro hexane digestion. Extracts included omega-3, omega-6, hexadecanoic acid, thymol, and carvacrol. The amount of each fatty acid in the Oliveria oil was analyzed by gas chromatography-mass spectrometry. The amounts of omega-3 (7.55-16.02%), omega-6 (7.48-17.42%), and hexadecanoic acid (7.44-18.19%) varied among the different ecotypes. Total phenolic content of the samples was measured. The antioxidant activity of the fatty oils was assessed using the DPPH and ABTS assays. The antioxidant properties of the extracts ranged from 23.16 to 52.7%. The anti-diabetic and anti-obesity evaluation was conducted using α-amylase and lipase enzymes. The IC values for Oliveria oil ecotypes were 118.2 ± 6.5-28.13 ± 6.4 µg/ml for the α-amylase enzyme and 40.00 ± 2.5-66.3 ± 2 µg/ml for the lipase enzyme. All Oliveria oil exhibited antioxidant properties; Jahrom, Dakal, Behbahan ecotypes were strong inhibitors of the α-amylase enzyme, and four showed strong to moderate inhibitors. Our in-vitro results show that oils' inhibition abilities roots from their specific chemical components.