Grant narrowly missed out when the original squad was named in April but now joins teammates Sean Maitland and Stuart Hogg in Australia.
Ryan Grant was in South Africa with the Scotland squad but is preparing to fly over to join the Lions squad in Australia, becoming the fourth Scot on the tour, along with Stuart, Sean and Richie Gray.
Speaking to glasgowwariors.org Ryan Grant said: "It's amazing, I'm over the moon to get the call and I'm just processing it all at the moment really, it's a rollercoaster of emotions. I found out about an hour ago from Scott Johnson and then got a call from Guy Richardson.
"I thought I had a chance yesterday but I had other things on my mind out here in South Africa but to finally be in the squad and get out there.
"It's great for Glasgow to have three Lions on the tour, I'm looking forward to getting out there now and catching up with the boys."