A core member of the Scotland 7s setup, 24-year-old Miller has impressed during his 21 appearances for Edinburgh to date with his combative style of play and ability in open field.
Comfortable across the back-row, he has started six of Edinburgh's Guinness PRO14 matches to date in 2020/21.
The Longniddry-born flanker made his World 7s Series debut in Las Vegas in 2017, quickly establishing himself as a key member of the Scotland side.
An appearance at the 2018 Commonwealth Games on the Gold Coast followed suit, helping Scotland to a sixth-place finish.
Prior to joining Edinburgh Miller made 16 appearances for London Scottish, having come through the ranks at Melrose prior to turning professional.
Speaking on his signing with the Warriors, Miller said: "I'm ready to take the next step in my career and really test myself and I believe Glasgow is the right environment in which to do that.
"I've been really enjoying my rugby these last few seasons and I'm looking forward to playing Glasgow's free flowing brand of attacking rugby.
"Speaking to Danny [Wilson] he liked the attacking style of rugby that I developed through the 7s programme and that I enjoy playing.
"I'm looking forward to playing that exciting brand of rugby Glasgow are known to play and adding to the squad.
"I'm buzzing to get across and get started."
Fellow back-rower Darge makes the move along the M8 after one season at BT Murrayfield, having put pen to paper on his first professional contract in the summer of 2020.
It's in the blue of Scotland that Darge has caught the eye of national observers, however, having been a standout performer for Scotland U20 since his debut for the representative side in 2018.
Darge was then named Scotland U20 captain ahead of the 2020 U20 Six Nations, leading a team including future Glasgow team-mates Ollie Smith, Rufus McLean and Gregor Brown to an historic 52-17 win over Wales in Colwyn Bay.
"I'm looking forward to making the move to Glasgow," said the flanker.
"When I spoke with Danny he talked about what he looks for in his opensides and I think I not only suit the mould but I also suit Glasgow's style of play.
"From watching Glasgow this season, I think the club is going places. If you look at the side that played against Leinster there are a lot of young guys getting their opportunity and playing well.
"My main motivation right now is to play as much rugby as I can and I feel that Glasgow will be the best place for me to do that.
"I'm grateful for the opportunity to come into a new environment, prove myself and earn my right to wear the jersey."
Glasgow Warriors Head Coach Danny Wilson was delighted to finalise the signatures for the back-row duo, as he continues preparations for the 2021/22 season.
"I've watched Ally play in recent games for Edinburgh," he told glasgowwarriors.org.
"With his 7s background he's an evasive ball carrier and has a good skill set.
"Rory is an exciting young Scottish prospect.
"He stood out while playing for the U20s and impressed when playing in the Glasgow v Edinburgh training game at Scotstoun, and when he came off the bench against Leinster for his professional debut.
"He's physical on both sides of the ball and a talent for the future, and it's great to be adding more depth to an already competitive backrow."