The Dumfries Saints product graduates from a partnership contract first penned in the summer of 2022, having made his professional debut for Glasgow Warriors in January's Investec Champions Cup clash with Exeter Chiefs.
The 21-year-old has frequently caught the eye in the Super Series while plying his trade with Stirling Wolves, his all-action style and dynamism with ball in hand having made him a standout in the competition.
His performances saw him become an integral part of the Bridgehaugh squad's run to the 2023 Super Series Final, with Hiddleston turning in a Player of the Match-winning performance in the final to help the Wolves lift the trophy.
The hooker packed down in the middle of the front row for the first time in Glasgow colours at Sandy Park, playing almost an hour on his first professional start.
"I'm over the moon," Hiddleston told glasgowwarriors.org.
"To have been on a partnership deal first of all, then to get the chance to go all the way and become a full-time pro, it's an incredible feeling.
"I'm still on cloud nine from my debut, to be honest! I was really nervous during the week, but as the game got closer I was absolutely fine and just relished the challenge.
"There's a great group of players here - you only have to look at the strength in depth at hooker. We're all competitive and push each other on, and it's a great chance for me to learn from some of the best hookers in Scotland.
"I just want to keep working hard and see what comes. I'm ready for any opportunity that comes my way."
Head Coach Franco Smith added: "Gregor is someone who we believe has a great deal of potential, and is a young man keen to learn and improve.
"He earned his opportunity to make his professional debut and he's a player who is still developing, something we are very excited about.
"We look forward to continuing to work with him, and to see him continue to develop over the coming years."