The Scottish Society for the Protection of Animals (SSPCA) said that the man found the Chilean rose tarantula last Tuesday, and kept his head enough to ring the organisation's hotline.
The SSPCA took it to the Glasgow Animal Rescue & Rehoming Centre in Cardonald, where it's been nicknamed Incy.
Caitlin Houston, animal rescue officer with the SSPCA, said: "While tarantulas frighten a lot of people, they are actually quite popular pets.
"Thankfully, the man who found this escapee wasn't too fazed and managed to contain him until I arrived. He was able to catch it using a glass and piece of cardboard.
"It's possible the tarantula belongs to someone in a nearby flat and we'd really like to return him home if he has gone missing.
"If no one comes forward we'll find him a new owner who understands his needs."
If anyone recognises this handsome creature, you can ring the SSPCA on 03000 999 999.