The 20-year-old junior defeated Australia's Tim Stewart 2 and 1 in his first appearance in the tournament, held at Royal Lytham & St. Annes in northern England. Weaver earned an invitation to the British Open at Carnoustie in Scotland from July 19-22 and to next year's Masters.
'This win is for the people we lost on April 16,' he said. 'I've been proud to represent the college here this week and to give them something positive.'
In the worst mass shooting in modern U.S. history, Seung-Hui Cho killed 32 people on the Blacksburg, Va., campus before committing suicide.
'There's been so much negative publicity about the place in recent months, and this is just a fantastic feeling to do something like this,' Weaver said.
Weaver matched Jay Sigel's win in 1979 and was the first American in the championship match since Jim Holtgrieve in 1983. This was the 22nd American win in 112 editions of the amateur game's most celebrated event.
Weaver was 2 up after the opening round of the 36-hole final and extended his advantage during the afternoon. He was 6 up before Stewart rallied to win four straight holes. Weaver held on, making par on the 35th hole.
'When Tim was fighting back I tried to tell myself that I was still in control of the match, but that gets hard to do when you lose four holes in a row,' Weaver said. 'The 17th was probably the most intense hole I've ever played, and when I finally closed the match out I couldn't believe I'd won.'