The good news is that a piece of the wait is already over, even if the full HBO Max debut is still pending. ‘Supergirl’ HBO Max Release Date PredictionsWarner Bros. has not yet announced an official HBO Max premiere date for ‘Supergirl’, but the studio’s recent release patterns offer a strong clue. If Supergirl follows a similar release pattern, it will likely begin streaming on HBO Max sometime between early September and late October 2026. Applying that same math to Supergirl’s June 26 opening puts an HBO Max debut around September 11, 2026. For now, all eyes remain on when exactly ‘Supergirl’ touches down on HBO Max, with September looking like the most likely landing pad.