The 19-year-old has only made one senior appearance for the Robins but the playmaker, who has come through the ranks at Ashton Gate, is hopeful that he can grab more chances of regular football.
"I've been working hard to get rewarded and I'm absolutely delighted with the new contract," said Reid. "I'd like to be a creative player, someone who can add goals and assists to the team.
"I've had a taste of first-team football and, like everyone else, I'm desperate to be involved at that level. I just have to keep working hard and be ready when the chance comes."
Manager Derek McInnes added: "Bobby's a great boy to have about; a hard-working lad. Bobby has two good feet, can see passes and is a confident lad. It's important we steer him in the right direction in terms of his education and development."
Reid spent a period on loan at Cheltenham Town last season before suffering an injury.