Systemic inflammation and oxidative burden in patients with type 2 diabetes mellitus (T2DM) causes deleterious cardiovascular outcomes. We sought to investigate the clinical antioxidative and anti-inflammatory effects of empagliflozin. Platelet function, oxidant and antioxidant biomarkers and pro-inflammatory agents at baseline and at 26 weeks were measured. A total of 95 patients (41.05% male, mean age 62.85 ± 7.91 years, mean HbA1c 7.89 ± 0.96%) with concomitant T2DM and coronary artery disease (CAD) were randomized (1:1) to receive empagliflozin (10 mg/daily) or placebo. Patients treated with empagliflozin had lower levels of interleukin 6 (IL-6) (adjusted difference (adiff): − 1.06 pg/mL, 95% CI − 1.80; − 0.32, P = 0.006), interleukin 1β (IL-1β) and high-sensitive C-reactive protein (Hs-CRP) (adiff: − 4.58 pg/mL and − 2.86 mg/L; P = 0.32 and 0.003, respectively) compared to placebo. There were elevations in super oxidase dismutase (SOD) activity, glutathione (GSHr), and total antioxidant capacity (TAC) with empagliflozin (adiff: 3.7 U/mL, 0.57 muM, and 124.08 mmol/L, 95% CI 1.36; 6.05, 0.19; 0.95, and 47.98; 200.18, P = 0.002, 0.004, and 0.002, respectively). While reactive oxygen species (ROS) improved significantly (adiff: − 342.51, 95% CI − 474.23; − 210.79, P < 0.001), the changes in catalase activity (CAT), malondialdehyde (MDA), or protein carbonyl groups (PCG) were not significant. Moreover, the P-selectin antigen expression on platelet surface was significantly reduced (adiff: − 8.81, 95% CI − 14.87; − 2.75, P = 0.005). Markers of glycemic status (fasting blood glucose, HbA1c, and HOMA-IR (homeostatic model assessment for insulin resistance) significantly improved (P < 0.001). Among patients with T2DM and CAD, 6-month treatment with empagliflozin can mitigate inflammation, platelet activity and oxidative stress and is associated with clinical cardiovascular benefits.Trial Registration Iranian Registry of Clinical Trials. www.IRCT.ir, Identifier: IRCT20190412043247N2. Registration Date: 6/13/2020. Registration timing: prospective