With the win, Boise State clinched a share of the Western Athletic Conference title.
Dinwiddie completed 22-of-31 passes for 273 yards. He had one interception, just his third of the season.
Tim Gilligan caught six passes for 149 yards and a score as the Broncos (10-1, 6-0 WAC) won their 16th consecutive conference game. They have not dropped a WAC contest since a 48-42 loss to Louisiana Tech in November 2001.
Paul Pinegar was 28-of-51 for 290 yards for the Bulldogs (7-5, 5-2 WAC). Pinegar's only touchdown pass, a 18-yard strike to Marque Davis, cut the deficit to 21-7 with 5:59 left in the second quarter.
Fresno State rushed for 311 yards in last week's 41-7 rout of San Jose State, but was held to just 48 yards on 30 carries by the Broncos.