In a statement, the force said: “A 28-year-old man has been charged in relation to an incident which occurred during His Majesty King Charles III’s visit to Luton yesterday.
“The man was charged under section five of the Public Order Act and has been bailed to appear at Luton Magistrates’ Court on January 9 2023.”
Charles was temporarily steered away from the crowds by his security staff shortly after arriving in the town.
He then continued to shake hands with members of the public after being moved to a different area.
The incident comes just weeks after 23-year-old Patrick Thelwell was arrested for throwing an egg at the King and Queen Consort during a visit to York.
The royal couple had just arrived in the city on November 9 to unveil a statue in honour of the late Queen at York Minster when a figure in the crowd threw four eggs, all of which missed.