The man spotted the creature while cleaning his kitchen on Tuesday and contacted the Scottish SPCA.
The Chilean rose tarantula is now in the care of the charity's Glasgow Animal Rescue and Rehoming Centre in Cardonald, where he has been nicknamed Incy.
Animal Rescue Officer Caitlin Houston 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."
Anyone who recognises the tarantula is being asked contact the Scottish SPCA's centre in Glasgow on 03000 999 999.