Up to 15,000 people are due to gather for Eid celebrations to mark the end of Ramadan.
The event will take place at the Baitul Futuh Mosque in Morden, south London - the largest mosque in western Europe.
His Holiness Hadhrat Mirza Masroor Ahmad - the Khalifa of Islam, a figure similar to the Pope in Catholicism - will deliver a live sermon which will be shown live on television to more than nine million people and translated into seven languages.
The Eid celebration, which is expected to last for around two hours, is for the British-based Islamic group Ahmadiyya Muslim Association UK. The group has been praised for its commitment to peaceful co-existence and charitable works.
In June, Home Secretary Theresa May spoke at an event in the House of Commons marking the centenary of the establishment of the Ahmadiyya Muslim Community in the UK.
The branch of Islam was founded in the late 19th century in India, but its leader has been based in Britain since 1984 as a result of persecution in Pakistan, where they are officially declared non-Muslims.
The event was attended by senior political figures including Deputy Prime Minister Nick Clegg, shadow foreign secretary Douglas Alexander and climate change secretary Ed Davey.
Mrs May said the Ahmadiyya were subjected to persecution in Pakistan and threats in the UK. "I know that you have been targeted as a community yourselves, particularly in Pakistan, where it is a criminal offence for Ahmadis to call themselves Muslims, and where you have been subjected to some horrific attacks," she said. "There have also been incidences of prejudice here in the UK where Ahmadi businesses have been boycotted, mosques attacked and television channels have broadcast programmes inciting hatred against you."
Mr Clegg told the event that the Ahmadiyya community had been "steadfast" in communicating a message of peace, love and reconciliation throughout the world. "Those are messages which are enduring, are powerful at all times and down all the ages and in all places and in all communities," he said. "Those messages of peace, of love, of respect towards one another, of reconciliation, these are messages that are especially valuable and serve as a particularly powerful antidote at a time of tension, at a time where we have seen, unfortunately, incidences of violence, of brutality, of extremism, which play no role in any peace-loving society."
Mr Alexander praised the work of the group in promoting peace and reconciliation. "In a world of ever greater diversity and ever greater challenges that message is needed as never before," he said.