Well, twice, actually. The first time was when he masterminded the death of his narco-boss, Gus Fring, one of the most wonderful villains in TV history. "We won," said Walter White. And one of the most extraordinary TV series in history could have ended right there and been just fine.
But Walter's journey to hell, told in the one of the most remarkable series ever seen on TV, wasn't finished at that triumphant moment. In true Breaking Bad style, more plot twists and turns and transformations were yet to come. God (and the showrunner) wasn't finished with him. His pride, his ego, his greed and delusions were still keeping the most unredeemable of men from redemption. Until one of the most perfect endings possible.
In a beautifully played scene between Walt and his wife, Skylar, the lies end --no more deluding himself that his single-minded journey to hell was a heroic effort to save his family. No, none of that. And in facing his deepest truth, he managed to redeem and finally put right, in some small measure, what he had caused to break so badly in the first place. After which, satisfyingly, he died a happy man, in a place where he found his one true calling -- being a chemist at the top of his game, making a product nobody else could produce, an artist, the master alchemist.