The prize will go to the builders of the first robot to send back video as it travels over 500 metres of the Moon's surface.
Competition organisers hope to spur the development of low-cost robotic space exploration.
The Google-sponsored Lunar X-Prize will be fought over by 29 teams from 17 different countries.
Organisers believe that the competition - first announced in 2007 - could have a winner by 2015.
"The official private race to the Moon is on," said Peter Diamandis, chief executive of the X-Prize Foundation.
The teams come from a wildly divergent background, ranging from non-profit consortia and university groups to well-funded businesses.
Several of the teams have already bought rides on spacecraft to transport their robots.
Astrobotic Technology, a spin off-off from Carnegie Mellon University has signed a deal with SpaceX - the private space company set up by PayPal founder Elon Musk - to use its Falcon 9 rocket.
Meanwhile, government-backed space agencies are also planning to send craft to the Moon.
Spacecraft from a joint Russian and Indian team and a separate one from China are pencilled to set off for the Moon in 2013.
But the X-Prize's backers think the future of space exploration will be driven by privately-funded groups.
"The most successful and revolutionary discoveries often come from small, entrepreneurial teams," said Tiffany Montague, of Google Space Initiatives.
The final line-up of teams competing for the $30 million (£18.5m) robotic Moon-explorer prize has been confirmed.