Loo-Loo, formerly called Armitage after the toilet she was found in, was rescued from Cashinos in Morden last month.
She has now joined two other chickens living with the RSPCA's hen expert.
"She's missing quite a few feathers but she's on the mend and settling in well," said Mia Fernyhough.  "It's an absolute mystery how she ended up where she did."
"We'll never know what happened to her."
Loo-Loo is believed to be an Aseel hen, a particularly intelligent breed that originated in India and Pakistan.
When she was found in the Surrey casino, she was dehydrated and too exhausted to fly, said Ms Fernyhough.
"My hens Matilda and Rachael were a bit unsure of Loo-Loo at first as she's quite different to them, both in appearance and - at first - in behaviour too. Loo-Loo didn't seem to recognise chicken food or the trough it's fed to them in so I think she may have been fed kitchen scraps.
"She watches my other hens and copies them so she is quickly getting the hang of things."
A chicken that was found drinking from a toilet in a casino has a new home.