Madonna and Beyonce have added their names to the multi-network Hope For Haiti Now telethon.
The star-studded fundraiser will also feature Denzel Washington, Brad Pitt, Leonardo DiCaprio and former US president Bill Clinton.
Madonna will perform from New York and Beyonce will perform from London.
The list of musical performers already includes heavyweights such as Bruce Springsteen, Alicia Keys, Stevie Wonder, Taylor Swift, Justin Timberlake and Keith Urban.
An estimated 200,000 people were killed after the powerful earthquake struck Haiti last week, devastating the nation.
The two-hour telethon will be shown on all the major US networks and a host of other channels. It will be broadcast from New York, London, Los Angeles and Haiti.
People can begin donating even before the start of the 8pm US-time concert via phone and text. Viewers can also download musical performances from the show via iTunes for 99 cents (61p). Those profits will also be donated to Haiti relief.
Actor DiCaprio announced he was donating one million dollars (£610,000) to the Clinton-Bush Haiti Fund, the relief effort led by former US presidents Bill Clinton and George Bush, and one of the organisations benefiting from the telethon.