The runaway mammal was spotted in March, and eventually caught after a protracted "cat and mouse" chase which ended on the roof of a house.
Volunteers at Fenland Animal Rescue found a microchip, showing she was registered in France.
"We think she hopped in a lorry in Calais," said volunteer Josh Flanagan.
"Her microchip has never been noted as being imported, and it was confirmed that she escaped her enclosure in France."
French authorities "weren't interested in repatriating her", he said, so she was sent to a sanctuary in Kent.
Mr Flanagan and his team had looked after the "rather vicious" raccoon since the rescue, which began when the critter was seen on top of a house in Broughton.
They were surprised to find out the "devilish" creature was, in fact, French, he said.
"We've had reports of a stray raccoon several times since September, so it's likely she's been living rough and fending for herself since then," he added.
She was eventually homed at the sanctuary near Rochester, "where she can live in a safe and secure environment with other raccoons to call friends", Mr Flanagan said.
The raccoon, or raton-laveur in French, is native to North America, and not usually found in the UK.
A raccoon that turned up in Cambridgeshire may have travelled across the Channel from France in the back of a lorry, its rescuers believe.