'We are back!'
The descent on to Mars is so dangerous that Nasa installed a system on their rover to send back information during the drop.
The landing sequence slowed the craft from 12,000 mph (19,000 km/h) to a complete stop in six minutes.
Nasa chief Sean O'Keefe congratulated mission officials.
He said: "This is a big night for Nasa - we are back!"
A second Nasa rover, Opportunity, will touch down in the other side of Mars in late January.
The £545 million rovers will check rocks with cameras, microscopes, rock grinders and other instruments.
Spirit should start its hunt for water on about 11 January.