Queen, fronted by singer Adam Lambert, has re-enacted its entire legendary 1985 Live Aid performance at the Fire Fight Australia concert for bushfire relief in Sydney.

Key points: 75,000 people attended the concert at Sydney Olympic Park

75,000 people attended the concert at Sydney Olympic Park Comedian Celeste Barber opened the show with a dig at politicians

Comedian Celeste Barber opened the show with a dig at politicians Queen, fronted by Adam Lambert, performed a repeat of its iconic 1985 Live Aid show

The concert featured 10 hours of musical performances raising funds for communities devastated by the catastrophic bushfires and the emergency services who have worked tirelessly to support them.

A total of $9.5 million was raised by the end of the live show, which concluded with a performance by John Farnham and Olivia Newton-John.

Queen's set began with the gentle piano intro of Bohemian Rhapsody, which then segued into Radio Gaga, as Freddie Mercury famously did at the 1980s fundraiser.

The audience appeared to be singing every word, joining in with gusto to the famous handclap motif.

As a nod to the former frontman who died in 1991, a recording of Mercury's "aye oh" call back from Live Aid was used, echoed enthusiastically by the crowd.

As Mercury did, Lambert — who has been touring with the remaining original Queen line-up since 2014 — followed swiftly into Hammer to Fall and the foot-stomping spectacular of We Will Rock You.

Lit phones were held aloft throughout the stadium and voices were in full force for the final song, We are the Champions, in what seemed to be a rallying cry for all, amid a set that was a memorable piece of rock history.

Celeste Barber hosts star-studded show

Comedian and social media star Celeste Barber hosted the concert. ( AAP Image: Joel Carrett )

The host, comedian Celeste Barber, whose own fundraising efforts have raised $51.3 million through a Facebook campaign, launched the show with an early political dart.

"It's been such a hectic time. As Aussies, we bear together and look after each other — because it turns out the people at the top don't," she said to a big cheer from the crowd.

Barber told fans they were in for a "wicked night" with "epic" names like Olivia Newton-John and Alice Cooper, plus "multiple costume changes" by herself, she joked.

About 75,000 attended the concert at Sydney Olympic Park, with 23 artists performing at an event that was broadcast nationally and to the US, UK and New Zealand.

More than 70,000 people attended the concert. ( AAP Image: Joel Carrett )

To celebrate, she thanked donors and led the audience in a chant of "power to the people".

"We are all here for each other," she said.

Alice Cooper brought some big-stick energy to the stage. ( AAP: Joel Carrett )

The announcement came after performances by pop favourite Jessica Mauboy and a blistering set by party-starters Peking Duk, who urged the audience to visit affected communities and holiday in Australia to help boost recovery efforts.

Waving an Australian flag, Delta Goodrem, accompanied by a choir of young girls all dressed in white, started her set with a rousing version of I Am Australian, joined by the crowd.

In a filmed message from Kensington Palace, Prince William said he and Catherine were "shocked and saddened" by the bushfires and commended the bravery of all those who put their lives on the line.

He spoke of the impact on livelihoods and thanked all those who had donated for their generosity.

"We wish you all the best," the Prince said.

Old and new national treasures and a few notable international faces were among those fronting the show.

Delta Goodrem, backed by a young girls' choir, got the crowd going with a rendition of I Am Australian. ( AAP: Joel Carrett )

Irish singer Ronan Keating and ARIA hall-of-famer Tina Arena were other crowd-pleasers that pledged their support and spoke about how much the day meant to them.

Things went up a notch again with Alice Cooper, whose unique brand of shock-rock theatrics would have blown the roof off Stadium Australia if it had one.

Bearing a cane and changing outfits despite his short set — including a white top hat and tailcoat featuring an Aussie flag — he powered through hits including Department of Youth, Poison and School's Out to a roaring crowd.

It was a hard act to follow, but Aria award-winning Gold Coast singer-songwriter Amy Shark stepped up, saying it was the "greatest day of my life".

After a short set of hits including Mess You Up, she signed off with anthem I Said Hi, saying it was a song written when she felt misunderstood and underappreciated.

"Standing here right now in front of you and everyone at home, we should feel strong and powerful right now, because we are the strongest country in the world," she said.

Before Sydney's own 5 Seconds of Summer took to the stage, host Barber led a tribute to all the firefighters — with at least 1,000 present — by asking the entire audience to stand and thank volunteers for their dedication and hard work. The request met with the loudest of roars.

Michael Buble also joined in proceedings with a live cross from his concert in Melbourne.

Jessica Mauboy was among a host of high-profile acts performing in Sydney. ( AAP: Joel Carrett )

A rare moment of stillness in the night began with a short clip of Russell Crowe, who introduced a minute's silence for the 33 men and women who lost their lives in the bushfires.

"May our actions in the days ahead be guided by the legacy they leave behind," he said, as the crowd fell silent.

This was followed by a spellbinding performance by Canadian singer kd Lang, who had flown in especially for the show.

She sang The Valley, with its heartrending line "You will walk in good company," followed by a spine-tingling version of Hallelujah.

Icehouse's performance of their iconic Great Southern Land impacted deep emotionally given the context of events — compounded by a transcendental intro by Aboriginal didgeridoo player William Barton.

Farnham, briefly joined by Newton-John for Two Strong Hearts, led the final song of the night.

It could only be You're the Voice, an anthem performed with Aboriginal artist Mitch Tambo and Queen's Brian May.

In the final moments of the song, a parade of firefighters took centre stage — a fitting end to a triumphant day marking the tragic times of recent months.

Indeed, despite the array of incredible artists, the spotlight was always on the people: the firefighters, the emergency services, all those who lost loved ones and all those affected by the fires.

John Farnham and Olivia Newton-John performed together. ( AAP Image: Joel Carrett )

Fans thrilled to be involved

Fans arrived at the stadium early and said they were excited to be a part of such a huge national event.

"It was a good opportunity to listen to some good singers and come together to support the firefighters and all those families that lost their homes," said Jacqueline Rook, attending with her husband Stephen and daughters Michaela, 14, and Savannah, 11.

Jacqueline Rook attended with her family. ( ABC News: Sarah Thomas )

It was a sentiment echoed by Rachel Gleeson and Emma Carr, both from Newcastle, and Rowena O'Neill from Bardwell Park.

"We're here to get behind our country. When things fall to pieces, we need to pull together and stand together, so that's why I wanted to come," Ms Carr said.

Ms O'Neill said she had family and friends on the South Coast who were not yet getting the support they needed. But she had seen the negative commentary surrounding Barber's fund and was aware it was for the national fire services.

"People are complaining that the $50 million is not going to the people — that's not meant to go to the people, that's meant to go to the RFS because they need better trucks and a lot more support so they can get out there and fight these fires," she said.

Friends Rachel Gleeson, Emma Carr and Rowena O'Neill outside the concert. ( ABC News: Sarah Thomas )

Country star Lee Kernaghan, a long-time advocate for rural communities, was the first act up after the Welcome to Country.

He finished his four-track set, including favourites Backroad Nation and Ute Me, with a tribute to the emergency services before launching into his anthem Spirit of the Anzacs.

"I want to send it out with love and respect for our frontline emergency services and to our men and women in uniform today past and present," he said.

"This really is reminding me right now that we live in the greatest country on Earth," he said to the rapturous crowd.

"Australia — but it's the Australian people who make this country great, so thank you to you and everybody involved."

The show also featured artists including Guy Sebastian, Pete Murray, Grinspoon, Conrad Sewell, Baker Boy and Daryl Braithwaite.

Brett and Nikki Wall came down from the Gold Coast to join their son, who lives in Dee Why in Sydney's northern beaches.

They said they came armed with water and lollies to get them through the day, and they hoped the money raised went directly to the "right areas".

"We came today to help support the firefighters and I hope the money goes straight to the people that need it," Mrs Wall said.

"The poor wildlife really need our help too."

Brett and Nikki Wall from the Gold Coast and their son from Dee Why. ( ABC News: Sarah Thomas )

Mr Wall said it was very Australian to get behind the concert.

"The spirit of Australia comes through, especially in times of need," he said.

"Look at when overseas countries have problems, we are the first one to send aid. It's the true Aussie spirit coming out."

'Really proud to be a part of this'

After his set, Kernaghan told the ABC he was relieved to have got the first performance out of the way but he was honoured to be a part of the event.

Country star Lee Kernaghan was the first artist to perform. ( AAP Image: Joel Carrett )

"I just feel really proud to be a part of this incredible concert and the audience here is love personified," he said.

"They've all come together, they've wrapped their arms around all those affected by the fires and [want] to try and make a difference with the fundraising.

"It's just been devastating for so many people and I don't think anyone could fully comprehend the impact of losing your home and all your belongings, or losing a loved one."

He also again paid tribute to the firefighters.

"Seeing the firies on the front line facing massive walls of flames and putting their lives on the line for other people, and those volunteers, what they did, they are extraordinary people," he said.

Weather conditions were perfect at the stadium. All concert profits will go towards rural and regional fire and rescue services, the Red Cross Disaster Relief and Recovery, the RSPCA Bushfire Appeal and the BizRebuild program.

People can donate to firefightaustralia.com.