Hill had 12 of his points on four straight 3-pointers as the Vandals (10-16) of the Western Athletic Conference took control of the game with a 16-5 run.
Idaho only had one basket over the final 5:27 but connected on 12 of 13 free throws.
The win was Idaho's first in Pocatello since 1996. The Vandals will rejoin the Big Sky Conference in 2014 for basketball and all sports but football, where they will be independent.
The game was part of the BracketBusters series, but the 101st between the schools.
Forward Kennedy Meeks, who has averaged 9.4 points and 6.5 rebounds at North Carolina, has pulled out of the NBA draft and will return to the Tar Heels.
Cal big man Ivan Rabb could have been selected in the top 10 of the NBA draft. Instead, he's returning to Berkeley to make himself, and the Golden Bears, stronger.
Devin Williams' decision last month to sign with an agent and enter the NBA draft has left West Virginia in a tough spot.