Fidget, a two-year-old black cat, is recovering at home after he was shot when he left the house for an early morning stroll.
The pellet caused so much damage to his leg that he had to undergo specialist surgery.
His owner Gemma Cope said will have to remain in a cage for 10 weeks while his damaged leg heals.
She now wants the person who shot her pet to be found and a prosecuted before they can strike again.
She said: "I cannot believe anyone could inflict such discomfort on an innocent animal. It will be another 10 weeks before we find out if he will make a full recovery.
"It is devastating to see a healthy cat having to be cooped up because he has a large brace on his leg. Fortunately his veterinary bill was covered by insurance, otherwise it would have cost us £2,000."
Ms Cope, 30, said she discovered Fidget had been shot when he limped into her home in the Greenhill area of Coalville last Sunday.
She said: "I first went downstairs at about 7am and Fidget was asleep.
"I went back upstairs and when I came down again at about at 8.30am he was limping badly.
"My partner thought he could have been run over or was suffering from an abscess as there was blood on his rear right leg.
"He was in great distress so we took him straight to the vets.
"They examined him and said he had been shot and had an air gun pellet lodged in a joint in his leg.
"They said it was in such a delicate position they were sending Fidget to a specialist veterinary hospital in Nottingham."
He underwent surgery at East Midlands Referrals and was taken home to Coalville on Thursday evening.
Ms Cope, who reported the incident to the police, said: "I would urge anyone who knows anything about what happened or saw Fidget limping in the street to contact the police so that the person responsible is caught."
She has another cat, a two-year-old female tabby called Fiji, who is missing her pal and now just sits outside his cage.
Police are investigating the incident and appealed for anyone with information to contact officers on 101.
