However, neither Harsin nor quarterback Joe Southwick will at the Hawaii Bowl.
While Harsin focuses on next season, Southwick has been dismissed from the team as Boise State goes for a team-record fifth straight postseason win Tuesday night when it faces struggling Oregon State in Honolulu.
The Broncos (8-4) have reached a 12th straight bowl, but this one will be different. For the first time in that stretch, Chris Petersen won't be on the sideline after he was hired by Washington.
Harsin was the offensive coordinator under Petersen for the Broncos' undefeated 2006 season, which ended with a BCS bowl win. He starred as their quarterback from 1995-99.
"A millisecond," Harsin said of making the decision after guiding Arkansas State to a 7-5 record in his first season as coach.
"This program personally has changed my life," he said. "It's made me who I am today. It's made my family and our relationships where they are today. So as far as the dream of this; all I wanted to do is get back here and do for this program what it's done for me. I'm proud to be in that position, and come in after guys who have been successful."
While Harsin was eager to replace Petersen, assistant Bob Gregory will be in charge in Hawaii.
Gregory dismissed Southwick from the team on Friday and sent him home after he was accused of urinating from a hotel balcony in Hawaii. Southwick, who finished the season with a 72.6 completion rate for 1,654 yards and 12 TDs and five picks, took a polygraph test after arriving in Boise in his bid to prove his innocence.
Grant Hedrick is expected to get the start in the bowl but the offense shouldn't suffer. In 12 games this season, he completed 135 of 198 passes for 1,443 yards and 15 touchdowns.
Ajayi finished second in the Mountain West Conference with 1,328 rushing yards while averaging 5.9 per carry with 18 touchdowns - one receiving. The sophomore running back was superb in every facet of Boise State's 45-17 season-ending win over New Mexico on Nov. 30, racing for 147 yards and a TD on 22 carries, while grabbing four passes for a career-high 105 with another score.
Miller had career highs of 77 catches, 934 yards and 11 touchdowns, and the junior wide receiver scored nine of those over the last four games.
The passing game may be in for a test since Oregon State (6-6) allows an average of 235.0 yards through the air, while ranking second in the Pac-12 with 19 INTs. Cornerbacks Steven Nelson and Rashaad Reynolds has six each to tie Arizona State's Robert Nelson for the league lead.
The Beavers weren't nearly as impressive against the run, surrendering an average of 193.2 yards, only better than Colorado's conference-high 208.5.
The defense was an issue in the regular-season finale, giving up 568 total yards, including 12 on a touchdown with 29 seconds left in regulation to fall 36-35 to then-No. 12 Oregon on Nov. 29.
Oregon State will likely rely heavily on the passing combination of Sean Mannion to Brandin Cooks, the Biletnikoff Award winner.
Cooks set a Pac-12 record with 120 catches, while his 1,670 yards are just 51 shy of the conference mark set last season by Southern California's Marqise Lee. He also led the conference with 15 receiving touchdowns, while rushing for two more.
The junior set a team record with 14 receptions in a win at San Diego State on Sept. 21.
Mannion, though, hasn't come close to being that prolific, throwing 11 interceptions compared to seven touchdowns over the last five games - a stretch that drew Oregon State's bowl status into question. He tossed 29 touchdowns and three picks through the first seven contests, as the Beavers nearly cracked the Top 25 with 79 votes.
Coach Mike Riley, though, is looking forward to visiting Hawaii.
"I am thrilled that our football team has an opportunity to play another game at an exciting destination against an outstanding opponent in Boise State," Riley said.
Oregon State leads the series 4-3, but the Broncos won the last meeting at home in 2010.