The law graduate impressed judges Mary Berry and Paul Hollywood to take the title ahead of James Morton and Brendan Lynch.
Challenges on tonight's show included making a Pithivier or puff-pastry pie, a fondant fancy challenge and a showstopper with chiffon sponge.
"His thought processes, his design and his baking, for the first time, have just joined up," Hollywood said of Whaite. "I'm very proud of him. He did exceptionally well."
"I feel faint," Whaite said after he was announced the winner. "I feel really queasy about it. It's not sinking in. I cannot believe it, I'm so happy."
Digital Spy readers had backed Morton, with over 58% predicting that he would win The Great British Bake Off.
Lynch got 25.3% of the vote, while Whaite trailed in third with 16.5% of readers predicting he would win.
Whaite is now saving up to go to Paris and train as a pâtissier.
