The series of Live Earth concerts, organised in nine cities to raise awareness of climate change issues, began in Sydney.
Toni Colette, star of Muriel's Wedding, played in Sydney with The Finish, a band which also features her husband.
Live Earth was inspired by former US Vice-President Al Gore, who appeared as a hologram as the Tokyo gig began.
In Tokyo local favourites - such as rockers Rize - shared the bill with overseas acts including Linkin Park.
Japanese singer Ayaka urged fans to change their daily habits as a first step to reducing global greenhouse gas emissions.
Thousands of fans also gathered in Shanghai to see artists including Anthony Wong and Sarah Brightman.
Rapper Snoop Dogg was among the international artists playing in Hamburg.
Colombian singer Shakira opened the Hamburg concert, which also had Yusuf Islam and Katie Melua on the bill.
Beninese singer Angelique Kidjo urged the audience in Johannesburg to "Get your butt out there and do something."
Keith Urban and Alicia Keys were among the big names at Giants Stadium, New Jersey.
At the Copacabana beach in Rio de Janeiro fans got into the spirit of the event.