The award is handed out to the head coach who has "contributed most to his team's success."
MacLean made a splash in his NHL debut as a head coach after spending six seasons as an assistant with Detroit.
MacLean's Ottawa Senators surprised the league with a playoff berth and an 18-point improvement over last season's 13th place finish. The Sens also jumped from 26th to fourth in the league in goals per game.
"He makes the hard work fun in a weird way," said Senators forward Nick Foligno. "He's done a great job for us. He's just come in and gotten to know everybody really well and understand what makes you tick and that's what allowed everyone to play their best because he knows when to push buttons and when to let off and that's what I think makes him such a great coach."
Hitchcock took over the St. Louis Blues in early November with the team at 6-7-0. Since then the Blues went 43-15-11 and broke or tied 13 franchise records, including a 21-game home points streak and 30 home wins overall.
It's the fourth time Hitchcock has been nominated for the award, but the first in 13 years.
Tortorella guided the Rangers to first place in the Eastern Conference with a 51-24-7 record, their best regular-season performance since capturing the Stanley Cup in 1994.
The club's goals-against figure (187) was tops in the East, and they also led all teams in hits (2,419).
"It's a great honour for him," said Rangers star Brad Richards. "He has worked with this organization the past three years to build something, and 51 wins this year is just a testament to him and the organization and how the players have bought in."
Tortorella is the only one of the nominees to have won the award, when he led the Tampa Bay Lightning to the Stanley Cup in 2004.
Dan Bylsma of the Pittsburgh Penguins won the award last year.
The NHL also announced the nominees for Foundation Player Award.
Nashville's Mike Fisher, Toronto's John-Michael Liles and Matt Moulson of the New York Islanders were given the nod for the league's community service award.