The Bristol-based street artist shared a photo of the wall art on Instagram, which is Banksy's usual method of claiming a work as authentic. The artist captioned the picture: "Royal Courts Of Justice. London."
The artwork is on an external wall of the Queen's Building, part of the Royal Courts of Justice complex.
Banksy's stencilled graffiti is often critical of government policy, war and capitalism.
Last summer, the artist began an animal-themed campaign in the capital of nine works, which concluded with a gorilla appearing to lift up a shutter on the entrance to London Zoo.
Other notable works included piranhas swimming on a police sentry box in the City of London, and a howling wolf on a satellite dish, which was taken off the roof of a shop in Peckham, south London, less than an hour after it was unveiled.
Banksy has in the past also been known for his work in the West Bank.
In December 2019 he created a "modified Nativity" at a hotel in Bethlehem which showed Jesus' manger in front of Israel's separation barrier, which appeared to have been pierced by a blast, creating the shape of a star.
Israel says the barrier is needed is to prevent infiltrations from the West Bank but Palestinians say it is a tool to grab land.