Maclean, 45, beat 47 other professional chefs over seven weeks of cooking to be named winner by Marcus Wareing, Monica Galetti and Gregg Wallace.
After his win, he said: "What an amazing journey. This is the biggest competition any chef can put themselves through and to be standing here at the end is incredible.
"I've hit emotions that I never knew I had, all in 30 seconds of each other.
"Words can't describe it. I never thought I would win, ever. My wife and kids are going to go absolutely nuts."
Maclean defeated rivals Elly Wentworth, 24, and Matt Healy, 33, in a gruelling final in which he designed and prepared a Michelin-standard dish for 28 Michelin-starred chefs and travelled to Oslo, Norway, to cook at renowned restaurant Maaemo to learn from three Michelin-starred chef Esben Holmboe Bang.
The final task was to create an exceptional three-course meal for judges Wareing, Galetti and Wallace in three hours.
Maclean's winning menu was made up of a razor clams starter, a Highland roe deer main course and a chocolate pistachio ganache pudding.
Two Michelin-starred chef Wareing hailed the starter as "the best razor clam dish I've ever eaten", adding that it "could come from any three Michelin-starred restaurant in Europe".
After Maclean was announced as the winner, Wareing said: "Gary has soaked up every little bit of this competition. He's lived the MasterChef dream. He's a major talent, he's grown incredibly well, and he's a gentleman of the kitchen."
Galetti added: "Gary has been such a pleasure to watch rediscover himself as a chef. He's a chef who always cooks from the heart and you can feel the emotion that goes into his cookery."
Maclean, who is senior chef lecturer at the City of Glasgow College, said he decided to enter the competition because of his love for the show.
He added: "The main reason I applied was that every year, my kids and students asked why I haven't done it.
"Getting to the finals is the hardest test a chef can put themselves through and I don't think people realise how long a journey it is, but my wife and kids have been with me every single step of the way, so it's been brilliant."
"Winning MasterChef: The Professionals is totally unbelievable. The whole experience was remarkable and enjoyable from start to finish. I have met some amazing people, both in front of and behind the camera. The support I have received from family and friends has been humbling.
"Hopefully, taking part has shown that if I can still chase my dreams, I can inspire students to start chasing theirs."
Maclean still plans to continue teaching, saying: "Winning MasterChef: The Professionals is going to provide me with a unique platform that hopefully will open the door to some very interesting opportunities.
"I would love to use my experience in the competition to help enhance the profile of culinary education.
"If I was to dream the perfect project alongside teaching it would be doing more TV.
"I absolutely loved the environment and the teamwork it takes to pull something like this together. I have so much respect for the people that worked on the show. It's a very similar bond between the team that you would find in a very good kitchen, amazing to be part of."