Stadium chiefs say tickets are selling fast for this much anticipated initiative which is aiming to raise awareness of climate change and encourage the use of renewable energy.
The Millennium Stadium stage will see debut performances from the Super Furry Animals, The Darkness and Elbow - as well as The Strokes - and a return for both Embrace and The Manic Street Preachers.
The Manics played to a 64,000 sell-out crowd in Cardiff on Millennium Eve and returned alongside Embrace and a host of other acts for the Tsunami Relief Concert in January last year, also a capacity event.
"The Manics filled the stadium on their own for one of our first major concert events on Millennium Eve and with an ever growing line-up of top chart acts, which includes their Welsh compatriots The Super Furry Animals, we are expecting another great night out in Cardiff," said Millennium Stadium chief executive Paul Sergeant. "Our ticket hotlines are keeping the team of staff taking bookings throughout the day very busy, but with only three weeks left - and some major acts still to announce - we would like to encourage fans to get their tickets early to avoid disappointment."
The One Earth Concert's stated aim is to engage the public in positive action to tackle climate change, and to encourage one million Europeans to switch to renewable energy sources this year. It is a not-for-profit event with proceeds going to the UK-based charitable organisation ONE EARTH TRUST and tickets are priced at £40 each.
By logging on to www.ClimateChangeNow.com and switching to renewable energy people can reduce their CO2 emissions from household energy by a third or more. It is FREE to make the switch and only takes 5 minutes.
The concert will be broadcast to millions world wide and hopes to kick-start positive public action towards climate change - starting with the simple step of switching to renewable energy. This should cut carbon dioxide emissions from household energy by 2 million tonnes, enough to fill over 340 million cars.
"People are genuinely concerned about the effects of climate change, but don't know how easy it is to make a big difference. The concert will focus attention on the part we can all play in tackling climate change," said Michael Mathres, co-founder of Climate Change Now.