Freya, Chancellor George Osborne's cat, has been returned to Downing Street after turning up frightened and lost in Vauxhall.
Homelessness outreach worker Kate Jones found Freya far from home and identified the wandering feline from a tag on her collar.
Ms Jones, who works with Thames Reach's London Street Rescue, said she had lots of experience helping the homeless in London - but that it was the first time she had helped a cat find shelter.
She said: "I'm not so used to working with homeless cats but when we saw Freya we realised how distressed she was, we did the only right thing possible and helped her get off the streets too.
"Freya is a gorgeous cat and, just like the people we work with, deserved some help in getting home."
Freya spent the night on Ms Jones's pillow before being collected by Downing Street officials.
She had somehow travelled south of the river and at least 1.5 miles before being found.
Freya, who moved to Downing Street with the Osborne family in 2010, has reportedly gone missing before after disappearing from the family's Notting Hill home in 2009.
Questions were raised last year when Mr Osborne added a dog to the household at Number 11.
Lola, a young bichon frise, was said to be cat friendly.