The bodies of both animals were found with significant burns and the devices still attached following the attacks in Rotherham, South Yorkshire and Queensferry in Deeside.
Two other similar incidents were reported in Bradford, West Yorkshire, and Kenilworth, Warwickshire, but in both those cases the cats are thought to have survived.
The cruelty was revealed by the RSPCA on Tuesday as it demanded stricter controls on the sale of fireworks, especially in the run up to Bonfire Night and New Year.
Dr Mark Kennedy, an animal welfare expert with the charity, said: “Fireworks are extremely stressful and frightening for many animals.
“Around 62 per cent of dogs, 55 per cent of horses and 54 per cent of cats in the UK show signs of anxiety when they hear fireworks.
“All too often we hear heart-breaking stories of animals who seriously injure themselves in a blind panic after being spooked by fireworks.”
The demand came on the same day it was revealed a zebra had died at a Somerset zoo after being so spooked by nearby November 5 celebrations it bolted straight into an enclosure fence.
The animal — called Hope after it was born at the start of the coronavirus lockdown — perished at Noah’s Ark Zoon in Clevedon.
Larry Bush, managing director, said: “We’re feeling devastated by the loss … She was so full of energy and life and she was a very healthy young zebra. It is such a tragedy that she has lost her life, seemingly as a result of fireworks being set off at nearby events which were intended as a celebration.”