Canagliflozin is a sodium-glucose co-transporter 2 inhibitor that reduces glycemia as well as the risk of cardiovascular events. Our main objective was to analyze antidiabetic treatment de-intensification and the glycemic efficacy of replacing antidiabetic agents (excluding metformin) with canagliflozin in patients with heart failure and type 2 diabetes with poor glycemic control. In this observational, retrospective, real-world study, we selected patients treated with metformin in combination with ≥2 non-insulin antidiabetic agents or metformin in combination with basal insulin plus ≥1 non-insulin antidiabetic agent. Non-insulin antidiabetic agents were replaced with canagliflozin. Patients were followed-up on at three, six, and 12 months after the switch and a wide range of clinical variables were recorded. A total of 121 patients were included. From baseline to 12 months, the number of antidiabetic agents (3.1 ± 1.0 vs. 2.1 ± 0.8, p < 0.05), basal insulin dose (20.1 ± 9.8 vs. 10.1 ± 6.5 units, p < 0.01), and percentage of patients who used basal insulin (47.9% vs. 31.3%, p < 0.01) decreased. The proportion of patients who used diuretics also declined significantly. In addition, we observed improvement in glycemic control, with an increase in the proportion of patients with glycated hemoglobin <7% from 16.8% at three months to 63.5% at 12 (p < 0.001). Canagliflozin use was also beneficial in terms of body weight, blood pressure, heart failure status, functional class, and cardiovascular-renal risk. There were also reductions in the number of emergency department visits and hospitalizations for heart failure. Moreover, canagliflozin was well-tolerated, with a low rate of drug-related discontinuation. Mounting evidence from randomized controlled trials and real-world studies point to the beneficial profile of sodium-glucose co-transporter type 2 inhibitors such as canagliflozin in patients with heart failure.