The singer will headline the Peace One Day concert at London's Wembley Arena on September 21.
The show marks the last major event of the London 2012 Festival and is being billed as John's only London live performance this year.
James Morrison and 2Cellos will also perform at the concert, which will include a contribution from Peace One Day ambassador Jude Law and the organisation's founder Jeremy Gilley.
"When Jeremy and Jude came to see me and told me about Peace One Day and the Global Truce 2012 campaign I had to get involved and support them," John stated.
"I am looking forward to seeing everyone on the 21st September at Wembley Arena and thrilled that James is joining us for this wonderful event!"
Peace One Day is a non-profit organisation that aims to institutionalise the mantra of "peace, one day" annually on September 21.
Elton John's Wembley Arena show will be filmed in high definition and broadcast across the world. Tickets for the concert are on sale now.
Watch Elton John perform at The Queen's Diamond Jubilee concert earlier this year below: