Law helped organise a petition urging the UK to press France for a delay in demolishing the southern part of the camp
British celebrities including Jude Law gave performances at the "Jungle" migrant camp in northern France on Sunday to draw attention to the plight of refugees facing imminent eviction.
Law was seen weaving his way through the mud and makeshift shacks to the Good Chance theatre, which was set up by British volunteers last year.
Around 200 residents of the camp showed up to watch the performance by Law and a group of British actors, comedians and singers, including playwright Tom Stoppard.
The event was organised by Letters Live, which gets celebrities to read letters from famous historical figures, and Sunday's event included original writing by refugees living in the squalid camp on the outskirts of Calais.
Law also helped organise a petition to Prime Minister David Cameron, urging him to press France for a delay in the demolition of the southern part of the camp, which could start as early as Tuesday.
More than 96,000 people, including about 150 public figures, have signed the letter. Actors Benedict Cumberbatch and Idress Elba were among the names on the petition.
The letter calls on the government to allow children living in the camp who have family in the UK to be reunited with them “with immediate effect”. It also calls for the demolition to be postponed until children are granted protection within the French system or reunited with family in the UK, according to the Independent.
"These are innocent, vulnerable children caught up in red tape with the frightening prospect of the demolition of the Jungle hanging over them," Law said last week.
"David Cameron and the British government must urgently work with the French authorities to alleviate this humanitarian crisis."
The decision to bulldoze part of the camp is being challenged in court, with a ruling due on Tuesday.
Figures from charity Help Refugees show that there are 440 children living in the southern section of the camp, 291 of whom are unaccompanied.
The demolition by French authorities is part of efforts to discourage migrants from trying to smuggle themselves to Britain via the ferries or the tunnel under the Channel.
"Such an enforced move would uproot again those who have already had to abandon their homes due to war and persecution," read the celebrities' letter.
The presence of thousands of migrants in the camp who are desperately trying to reach Britain has become a political hot potato both within France and between Paris and London.
The latest estimates by the local authorities say there are 3,700 people living in the Jungle and the government has been trying to persuade them to move to welcome centres elsewhere in the country, particularly as the weather worsened in winter.
Announcing the demolition earlier this month, the French government's local representative Fabienne Buccio said: "The time has come to move on, no one must live in the southern part of the camp, everyone must leave this section."
She estimated that between 800 and 1,000 migrants would be affected.