Hillman, the Mountain West Conference Freshman of the Year, scored on runs of 22, 37 and 2 yards, and pulled in a 15-yard scoring pass from Ryan Lindley after a beautifully executed fake.
Lindley faked a handoff to Brandon Sullivan into the line, then hid the ball down by his right hip as Navy stood up the fullback. Lindley then hit a wide-open Hillman in the right corner of the end zone for a 28-14 lead on the first play of the fourth quarter. Hillman scored on a 2-yard run midway through the period.
"It was very surprising," Hillman said of his effort, the sixth time this season he gained at least 150 yards. "But the O-line, like I said, you could put a high school senior back there and he would have 1,000 yards behind this line. I can't say enough about them."
A few plays before his touchdown catch, one of Hillman's cleats came off and he hopped off the field, trying to keep that foot dry.
"My socks got wet," he said. "That's not a good feeling when you've got cleats on."
SDSU (9-4) hadn't won a postseason game since beating Boston University in the 1969 Pasadena Bowl. The Aztecs had been in only three bowl games since, most recently the 1998 Las Vegas Bowl, which it lost to North Carolina.
Hillman broke the previous Poinsettia Bowl record of 129 yards rushing by Navy's Adam Ballard in 2005.
Hillman also ran for 228 yards in a loss at Missouri on Sept. 18.
The Aztecs outrushed Navy 279-235.
"Defense, again," Hillman said. "It was a statement. They did a great job, stopping them the whole game."
Navy (9-4) was making its third Poinsettia Bowl appearance since the game's inception in 2005.
