A star-studded global broadcast to honour healthcare workers on the front lines of the battle against the coronavirus pandemic has begun online, and will culminate in a main concert overnight.

Irish stars participating in One World: Together At Home include Niall Horan, Hozier and Picture This. It is being curated by Lady Gaga and all participants are appearing remotely.

The two-hour television concert is being preceded by a six-hour livestreaming event.

British actress Jameela Jamil kicked off proceedings and celebrities who made early appearances included English soccer star David Beckham, who held a video chat with young athletes, encouraging them to keep honing their skills at home.

Adam Lambert performed a rendition of Tears for Fears' hit Mad World, while The Killers delivered a stripped-back version of Mr Brightside.

One World: Together at Home will air across RTÉ2, RTÉ Player and RTÉ 2FM on Sunday 19 April from 7pm. 

The two-hour programme will feature Doireann Garrihy and Eoghan McDermott, who will bring an Irish take on the global event.

The Rolling Stones announced yesterday that they would be joining the entertainment extravaganza, combining music, comedy and stories from doctors, nurses and grocery workers.

"We are honoured to be invited to be part of the 'One World: Together at Home' broadcast - from our homes in isolation," the group said in a statement released by Global Citizen, the nonprofit group that spearheaded the event with the World Health Organization (WHO).

Other stars taking part include Celine Dion, Billie Eilish, John Legend, Elton John, Paul McCartney, Chris Martin, Andrea Bocelli and Michael Buble.

The livestream opened with social media postings and news clips showing doctors and nurses being applauded by communities around the world, families greeting each other through windows, and acts of kindness in support of those who are isolated and frail.

Sarah Jessica Parker gave a shout-out to medical workers toiling at the hard-hit hospital Elmhurst in New York, the US epicentre of the coronavirus pandemic.

"You are heroes," the Sex and the City star said from her couch. "We are forever grateful for the sacrifices you have made to keep the community healthy and safe."

Jennifer Hudson belted out the Cats theme Memory and in a separate segment, actor Matthew McConaughey told the audience: "Let's remind ourselves here in these trying times there is still so much kindness, hope and joy in the world."

While the special is not billed as a public fundraiser, it is also aimed at encouraging philanthropists and companies to contribute to the WHO's Covid-19 Solidarity Response Fund.