Objective: We studied the effects of exercise training alone or combined with dietary supplementation of omega-3 polyunsaturated fatty acids (Ω-3PUFA) and oleate on metabolic syndrome (MSyn) components and other markers of cardiometabolic health. Methods: Thirty-six patients with MSyn underwent 24 weeks of high-intensity interval training. In a double-blind randomized design, half of the group ingested 500 mL/day of semi-skim milk (8 g of fat; placebo milk) whereas the other half ingested 500 mL/day of skim milk enriched with 275 mg of Ω-3PUFA and 7.5 g of oleate (Ω-3 + OLE). Results: Ω-3 + OLE treatment elevated 30% plasma Ω-3PUFA but not significantly (P = 0.286). Improvements in VO2peak (12.8%), mean blood pressure (−7.1%), waist circumference (−1.8%), body fat mass (−2.9%), and trunk fat mass (−3.3%) were similar between groups. However, insulin sensitivity (measured by intravenous glucose tolerance test), serum concentration of C-reactive protein, and high-density lipoprotein improved only in the Ω-3 + OLE group by 31.5%, 32.1%, and 10.3%, respectively (all P < 0.05). Fasting serum triacylglycerol, glucose, and plasma fibrinogen concentrations did not improve in either group after 24 weeks of intervention. Conclusions: Diet supplementation with Ω-3PUFA and oleate enhanced cardiometabolic benefits of intense aerobic exercise training in patients with MSyn.