The man was detained after the incident at Westminster Hall as thousands of people filed past the Queen’s coffin to pay their respects.
London’s Metropolitan Police said the somber mood was broken at around 10pm on Friday (7am Saturday ET) as live streaming from inside the venue briefly stopped.
In a statement, Scotland Yard said: “At around 10pm on Friday 16 September, officers from the Metropolitan Parliamentary and Diplomatic Protection Command detained a man in Westminster Hall following a disturbance.
“He was arrested for an offense under the Public Order Act and is currently in custody.”
It comes after the 19-year-old allegedly exposed himself and pushed mourners from behind as they queued at Victoria Tower Gardens on Wednesday.
The suspect, identified as Adio Adeshin, is said to have jumped into the Thames in an attempt to evade the police before emerging and being arrested.
He was remanded in custody on Friday after appearing at Westminster Magistrates’ Court on two counts of sexual assault and two counts of breaching a sexual harm prevention order.