Owner Tina Jaconelli was shocked when 11-year-old Khopa returned home with a wound on his chest.
While the 39-year-old assumed the cat had been fighting with another animal at first, she soon realised it was much more serious.
And after rushing Khopa to the vet, an examination revealed an airgun pellet was lodged in the poor moggy's chest.
Vets say it is too dangerous to remove the pellet because of severe swelling around it.
Tina, from Thornliebank, in East Renfrewshire, said: "It makes me sick.
"Whoever did this, from where they ended up hitting Khopa, must have been aiming for his head.
"We also think the gun was shot from quite a height, possibly out of a window.
"It just makes me so angry that someone would do this."
Khopa is understood to have been shot sometime between 9pm on Monday and 2am last Tuesday.
He doesn't wander far from his home, so it's likely that he was shot in the Thornliebank area.
Tina added: "We've lived here for eight years and have never heard of anything like this happening before.
"I'm worried about letting the cats out, but I can't keep them in, they're too used to being allowed out whenever they like.
"What frightens me the most is that whoever did this must have been hidden, and shot from a distance.
"Khopa wouldn't go near a person, he's a shy wee cat."
Khopa is on a host of pain-killers and antibiotics, to stop his wound from becoming infected.
"Thankfully, Khopa doesn't seem to be in a lot of pain, but his chest is very swollen", Tina said.
"He is on antibiotics to prevent infection, but apart from that, we can't do anything until the swelling goes down."
Tina, who recently opened a new business - Jaconelli's Barbers in Langside - has reported the horrific incident to police.
Businesswoman Tina is also a volunteer for animal charity, Cats Protection
A statement from the Cats Protection Giffnock and District Branch warned local pet owners about the "despicable" incident.
It said: "One of our volunteers' cats has been shot with a pellet gun in the Thornliebank area.
"He is ok, but has a pellet in his chest.
"This is despicable and we will not tolerate this in East Renfrewshire.
"Please tell all your friends and family, if you live in the area, to be alert."
A Police Scotland spokeswoman said: "We received a report of a cat being injured and advice was given to the owner."