Vet Dr. Joe Hollins scrubbed Jonathan's shell with a loofah, a soft brush and surgical soap carefully removing nearly 200-year-old black sludge.
The bath did not have any medical reasons and the keepers wanted to gloss Jonathan for a festive occasion: a Royal Family member is expected to visit the St. Helena Island, where the tortoise lives.
"Jonathan stood like a statue when I was washing him, I don't know whether that was the vibrations he found soothing or he was thinking 'At last, I've had my first bath!' the vet said as quoted by The Telegraph.
During the tortoise's life, eight British monarchs have been crowned and 51 prime ministers have served in the UK.