Adam Ant is set to headline an 80s nostalgia tour
On Monday evening police found the 47-year-old singer in the Camden Town area of north London after calls from the public regarding concerns for his safety.
He was taken to the nearby Royal Free Hospital and "sectioned" - legally confined - under the 1983 Mental Health Act.
The 1980s pop star had already been arrested on Saturday night after allegedly pulling out a gun in a pub.
'Safety'
The performer, whose real name is Stuart Goddard, was bailed to appear at Highbury Magistrates Court on Friday.
After Monday's incident the Metropolitan Police issued this statement: "Police were called at 7.15pm on Monday regarding concerns for the safety of a 47-year-old man.
"Police from Camden located him in the Camden Lock area and took him to the Royal Free Hospital.
"He has been sectioned under the Mental Health Act."
But the singer has protested "I'm not mad", according to the Sun newspaper.
'Abducted'
The Sun said that the singer had contacted the paper from the secure ward where he has been placed and said: "They've put me in the Alice in Wonderland ward because they think I'm crazy."
He claimed he was the victim of a conspiracy and had been "abducted by the police again".
Doctors will be able to hold the singer for up to 28 days, and will be able to decide if he is fit to plead at his scheduled court appearance in Friday.
He is charged with possession of a firearm or imitation firearm with intent to cause fear of violence, after Saturday's incident.
Acting career
He is also being charged with criminal damage and one charge of actual bodily harm on a man in his 40s.
The former punk and later teen idol - famous for dressing as pirates and highwaymen and wearing a white stripe across his face - sold millions of records in the 1980s with hits such as Prince Charming and Stand and Deliver.
Later that decade he moved to California to pursue an acting career, but returned to his native London after some years.
He has a daughter, Lily, who will be four in March.
Adam Ant recently stated his intention to release a single to help the New York firefighters.
He is due to headline a 1980s nostalgia tour in April.