The mayor of London is sending a three-wheeled bike, sponsored by Barclays, to Prince George as a gift.
He said he wants to 'acculturate' the Prince to the 'joys of cycling' at the earliest opportunity.
Speaking on his regular LBC radio phone-in show, Mr Johnson said City Hall was giving the royal baby a bike after a caller asked what he sent to Prince George.
"I'm sure all our listeners will be thrilled to know we are sending a tricycle," he said.
Whilst he doesn't know where it is from, he said: "I haven't personally been shopping, I'm sure it is a beautiful blue."