The theatre was evacuated and the rest of the show cancelled after activists climbed onto the stage during the first act.
Just Stop Oil said four protesters locked themselves to the stage using flexible bicycle locks at around 8.50pm.
In a post on Twitter, the group wrote: “Four people are locked to the stage of the French-revolution-themed show.
“Valjean steals bread to feed a starving child. How long before we are all forced to steal?
“The fossil fuel show can’t go on.”
🚨 BREAKING: Just Stop Oil interrupt Les Mis.
🦺 4 people are locked to the stage of the French-revolution-themed show.
💬 “Valjean steals bread to feed a starving child. How long before we are all forced to steal?
🌡 The fossil fuel show can't go on: https://t.co/3tlBID7nKA pic.twitter.com/nCXsIGINoS
— Just Stop Oil (@JustStop_Oil) October 4, 2023
In video of the incident, audience members can be heard booing the demonstrators.
The Metropolitan Police said that five people were arrested at the theatre.
In a post on Twitter, the force said: “At about 9pm tonight, police were called to a protest inside a theatre on Shaftesbury Avenue, WC1.
“Local officers were quickly on scene and five people have been arrested.”
William Village, chief executive of Delfont Mackintosh Theatres - which owns the Sondheim, said: “During the first half of our performance of Les Miserables, individuals from Just Stop Oil invaded the stage, abruptly stopping the show.
“Following our safety protocols, the audience were asked to leave the auditorium and the Met Police attended.
“Regrettably, there was insufficient time to enable us to complete the rest of the performance.
“Whilst we recognise the importance of free expression, we must also respect our audience’s right to enjoy the event for which they have paid.”
While many social media users complained about the protest, others also took issue with the group’s description of the show, pointing out that the Victor Hugo novel it is based on was set decades after the French Revolution and features instead the 1832 June Rebellion in Paris.
“Les Miserable[s] isn’t set during the French Revolution which you’d know if you bothered to do your research properly. It’s set in the 19th century starting in 1815 & culminating in the 1832 June Rebellion which took place in Paris,” wrote one user.
“Solidarity and that but it’s not set during the French Revolution,” added another.
Just Stop Oil replied: “Very true. Students spurred into action due to harvest failures, food shortages, and increases in the cost of living. Sound familiar?”
Just Stop Oil protesters halted an opera performance of Dialogues des Carmelites at Glyndebourne in June by setting off a confetti bomb and blowing an air horn.
Audience members booed and shouted: “Disgraceful!” before the protesters were removed from the auditorium. The performance resumed around 20 minutes later, and no arrests were made.