The Dark Energy Survey Supernova sample is the largest and deepest Type Ia Supernova (SN Ia) sample from a single telescope to date. It includes 1600 photometrically identified SNe Ia with high-quality multi-band light curves and spectroscopic redshifts. With a redshift range spanning between 0.1 to 1.2 and a well-defined selection function, this SN sample constitutes an ideal dataset for cosmology. In my talk, I will present the cosmological results from this unique sample and show that DES SNe, combined with publicly available low-z SN samples, provides excellent constraints on the Dark Energy equation of state from SN Ia. I will briefly discuss how the DES-SN compares to previous SN cosmological results and how these measurements, combined with BAO and CMB, seem to provide tantalizing evidences for evolving dark energy. Looking towards the future, I will discuss how future SN surveys like Rubin and Roman will revolutionise SN Ia cosmology and potentially answer some of the most pressing questions of modern cosmology.