At a special season ticket event at W5 in the Odyssey Pavilion on Monday night, the Giants revealed that Thornton was returning as head coach after a four-year absence.
And the Ontario native is delighted to be back in the city.
"I loved my time in Belfast and so did my family," Thornton told fans.
"I have missed this place and this team since the day I left. I am very excited to be back and I plan on being here for a long time."
Working for the Belfast Giants is very special, unlike any other hockey team.
Thornton first arrived in Belfast as a player during the second half of the 2002-03 season, joining the team that would go on to win the Giants franchise its first Playoff title.
As coach from 2008 to 2010, replacing Ed Courtenay, he led the side to British Knock-Out Cup and Challenge Cup wins and another Playoff championship.
Having since pursued a career outside of hockey, Thornton is now set for a big return to the sport.
"This is more than just a coaching job and Steve gets that," General Manager Todd Kelman said.
"He obviously played a huge part in the on-ice performance when he was here before, but he was instrumental in a lot of the off-ice changes that led to our success.
"He helped set up the scholarship programme we had with the University of Ulster and he changed the fundamental way we recruited our teams. I am really looking forward to having him back with the Giants."
Kelman added: "His role encompasses overseeing the hockey side of our business and the coaching of the team, but he will also be tasked with building links and developing our junior ice hockey in Northern Ireland."
This is not a one year contract to coach a hockey team. Steve is moving his family and his whole life here to take up a permanent role within our organisation.
As well as unveiling their new coach, the Giants also confirmed another big signing, with their Defenceman of the Year Calvin Elfring returning for another season.
The Alberta native, who joined the Giants last season after seven years in Germany's top league with the Straubing Tigers, racked up 13 goals and 37 assists for 50 points.
He was also named as the Elite League's Top Defenceman by the coaches and general managers and earned himself an All-Star team selection, alongside teammates Kevin Saurette and Rob Sandrock.
"It was a no-brainer for us to sign back Calvin for another year," Thornton said.
"Todd and I have been consulting on players for the last couple of weeks, and both of us had Elfring as a 'must sign' on our list."
Elfring joins defencemen Jeff Mason, Davey Phillips and Kevin Phillips, forwards Evan Cheverie, Mark Garside, Darryl Lloyd, Craig Peacock, Kevin Saurette, Colin Shield and captain Adam Keefe.
"We are currently talking to a handful of guys from last season's team still and should be able to confirm more signings very soon," Thornton added.
"As for new players to Belfast, I am not going to rush into anything. We have nearly all our Brits signed up right now and the core of our team back already.
"We are only going to need to add three to five new faces to an already solid team and we will make sure each of those guys fit into our plans."