It was the most passing yards the Utes have given up all year.
The Utes thought they could get to Halliday and rattle him, but his quick release was too much for the Utes, who went without a sack for the first time this season.
Utah was leading the nation with 36 sacks.
Utah coach Kyle Whittingham gave Halliday credit for the win.
"We couldn't cover them in man," he said. "We were thinking going into the game we could match up man-to-man to play a dose of it, but it was very apparent we were not matching up. In zone coverage we got disoriented with the under-coverage and they found those holes."
Utah had hoped to break its drought of interceptions in the game since Halliday has thrown 19 this year, but the Utes failed in that mission as well.
Most memorably, one Halliday pass bounced off the hands of linebacker Jason Whittingham. Then, in the fourth quarter, safety Michael Walker could have picked off a pass with the Utes trailing 43-37 but lost sight of the ball over his shoulder.
The Utes did recover two fumbles, but it wasn't enough as Halliday came up with one big play after another one.
It was a frustrating way for Utah's defense to lose a game considering how well it has played lately.
"They did a great job of getting rid of the ball faster than normal," Utah defensive end Trevor Reilly said. "There were three or four times I thought I was going to sack him and he got rid of the ball, so give him credit."
Halliday connected with 10 receivers: Marcus Mason led the way with eight catches for 88 yards and a touchdown while Dominque Williams had five catches for 154 yards and two touchdowns.
A closer look
WSU quarterback Connor Halliday was 39-of-62 for 488 yards against the Utes. Here is a look at how some other Pac-12 quarterbacks have fared against Utah:
Oregon State's Sean Mannion • 24-of-45, 443 yds, 5 TDs
UCLA's Brett Hundley • 17-of-27, 211 yds., 1 TD
USC's Cody Kessler • 21-of-32, 230 yds., 1 TD
Oregon's Marcus Mariota • 19-of-26, 288 yds., 3 TDs