Austin Wierschke retained his title in the contest that was held in New York's Times Square in front of hundreds of fans.
The event was sponsored by LG Electronics and the company's phones were used by the contestants.
This was the second time Austin had taken home the prize in two years. He collected $50,000 in prize money while beating 10 other participants.
Some of the tasks the contestants had to take part in included being blindfolded and having 45 seconds to type: "Twinkle, twinkle, little star, how I wonder what you are, up above the world so high, like a diamond in the sky."
After winning, Wierschke - whose mother coached him to send speedy messages - said: "I don't really know what to say."
Later, the teen winner spoke about being flown to Los Angeles and doing press interviews. He said: "It's been crazy. I've got to have done a lot of stuff a normal 17-year-old might never get to do in his life."
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