It touched down at 1144 local time (1544 GMT) after a successful 11-day construction and supply mission to the International Space Station (ISS).
During their stay in orbit, astronauts Dave Wolf and British-born Piers Sellers made three spacewalks to attach a 13.5-metre-long (45 feet) aluminium truss, or girder, to the space platform.
Dr Sellers told a news conference afterwards that it had been a "magical" experience for the crew of six.
Describing the journey into space, he said: "We go uphill and somehow we all step at right angles to our normal reality and we go to this island in the sky that is a completely different place.
"It has different rules; it is like nothing I have ever seen or even dreamed of before.
"Things float, you are climbing underneath structures like a spider underneath a gutter. It is a magical place.
"And then you take a sideways jump back into reality and come back here."
'Stunned'
He said he was "dazzled" and exhausted by his seven-million-kilometre (4.5 million mile) journey.
"I think we all feel tired and the tape hasn't rewound as to how the experience really was. I have got flashes of it.
"I feel physically tired, mentally a little tired but stunned, still dazzled by the whole experience. That's a rookie talking."
The truss fitted to the ISS features a sophisticated new cooling system. It will also be used to lock down future solar wings.
It forms part of a backbone structure that will eventually stretch more than 100 metres (330 ft).
The next truss is due to arrive on the Endeavour orbiter next month. The shuttle will also ferry up Expedition Six, the next crew to live on the station for an extended period.
No go UK
Piers Sellers is assured of a hero's welcome the next time he visits his homeland. His exploits 390 km (240 miles) above the Earth have been followed closely in Britain.
The atmospheric scientist became only the third UK-born astronaut to get into orbit and is the second to "walk" outside a spacecraft.
Originally from Crowborough, in Sussex, Dr Sellers became a US citizen to get on the US astronaut training programme.
This is the only way Britons can get into orbit because the UK Government will not fund manned space projects - not even through the European Space Agency of which it is a member.
'Awesome' experience
Dr Sellers' father-in-law, Philip Lomas, 71, from Hebden Bridge in West Yorkshire, said: "My wife was crying when they touched down. It was just like a big bird coming down - it was beautiful, gorgeous.
"The only thing with this mission is the English language does not have enough words. Apart from 'awesome' and 'wow' there isn't any way to describe what is happening."
Mr Lomas, who travelled to the US to watch the launch and stayed there for the duration of the mission, said that after emerging from the shuttle the crew, who "all looked great", had taken a traditional walk around the space ship.
"Piers looked very happy but tired, but then he has spent about 20 hours [spacewalking]. He told us he would be shattered for a week or two before he was back to normal."
Big grin
Dr Sellers' mother, Lyndsay, watched the return of Atlantis on the TV from her home in Tunbridge Wells, Kent. She told the BBC she thought her son would be keen to return to space if he got the opportunity.
"He'll want to do it again without a doubt. Mandy (his wife) said he had a grin going twice around his head up there so she's certain he wants to go back."