Brat had been a thorn in Cantor's side on the campaign, casting the congressman as a Washington insider who isn't conservative enough. Last month, a feisty crowd of Brat supporters booed Cantor in front of his family at a local party convention.
His message apparently scored well with voters in the 7th District.
"There needs to be a change," said Joe Mullins, who voted in Chesterfield County Tuesday. The engineering company employee said he has friends who tried to arrange town hall meetings with Cantor, who declined their invitations.
Tiffs between the GOP's establishment and tea party factions have flared in Virginia since tea party favorite Ken Cuccinelli lost last year's gubernatorial race. Cantor supporters have met with stiff resistance in trying to wrest control of the state party away from tea party enthusiasts, including in the Cantor's home district.
Brat teaches at Randolph-Macon College, a small liberal arts school north of Richmond. He raised just more than $200,000 for his campaign, according to the most recent campaign finance reports. Prominent national tea party groups did spend independently to help Brat.
Brat offset the the cash disadvantage with endorsements from conservative activists like radio host Laura Ingraham, and with help from local tea party activists angry at Cantor.