The black and white male, thought to be around 10 weeks old, was discovered with a broken spine and unable to stand in an underpass near Wessex Gardens in Andover, Hampshire, last Sunday.
He was taken to a local vet but was put down due to the severity of his injuries, which may have been caused by being swung by the tail.
The RSPCA received 770 calls between Christmas Eve and Boxing Day, with 192 related to abandoned animals.
The charity is expecting to take in 19,000 animals throughout December and into January.
RSPCA inspector Alan Browning said: "While many people were getting ready to enjoy Christmas this kitten was being subjected to horrendous cruelty that sadly cost him his life.
"He was found in a carrier bag, paralysed and was unable to stand, by a gentleman walking home from the local Tesco store.
"He was rushed to a veterinary surgeon and found to have a fractured spine probably due to being swung round by the tail.
"It is unthinkable why somebody would treat a defenceless animal in such a way."
Anyone with information is urged to contact the RSPCA's appeal line on 0300 123 8018.
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