"Couldn't have picked a clearer day," commander Charles Hobaugh said. Mission Control congratulated him on a "picture perfect" landing.
It was an especially sweet homecoming for two of the crew.
Astronaut Nicole Stott was away for three months, living at the space station. Fellow crew member Randolph Bresnik's baby daughter was born last weekend.
"Everybody, welcome back to Earth, especially you, Nicole," Mission Control radioed.
Hobaugh and his crew spent a week stockpiling the space station. They delivered big spare parts and performed three spacewalks to install equipment and carry out maintenance.
The pumps, gyroscopes and storage tanks should keep the outpost in business for another five to 10 years, long after Atlantis and the two other shuttles are retired.
Stott was feeling the full effects of gravity for the first time since she rocketed to the space station at the end of August. Her mission lasted 91 days.
She said all week that she couldn't wait to see her husband and 7-year-old son, who were at Kennedy Space Center for the landing. She also was looking forward to some pizza and icy cola.
Bresnik had even bigger plans: to hold his infant daughter for the first time.
Abigail Mae Bresnik was born Saturday night, right after her father took his first spacewalk. But he'll have to wait until Saturday to see her. Bresnik's wife, Rebecca, stayed home in Houston with Abigail and 3-year-old big brother Wyatt.
Atlantis -- which brought back broken equipment from the space station's water-recycling system -- logged 4.5 million miles and circled Earth 171 times.
This was Atlantis' next-to-last mission. Only five shuttle flights remain, all to the space station next year. Station construction will essentially end at that point, so NASA used the trip to send up as many hefty spare parts as possible. None of the other visiting spacecraft -- from Russia, Japan and Europe -- can carry so much in a single load.
Atlantis, which delivered nearly 15 tons of gear, left the space station 86 percent complete.
NASA's next shuttle flight is in February. Endeavour will deliver a full-fledged module to the space station, complete with a cupola for prime Earth gazing with a domed chamber that has seven windows.
The five remaining space station residents, meanwhile, may have to dodge a piece of space junk this weekend.
NASA said Friday that flight controllers were monitoring a large piece of an old Delta rocket that could pass within an uncomfortably close six miles of the outpost Saturday afternoon. The rocket was used to launch NASA's Stardust spacecraft in 1999 to gather comet dust samples.
A decision on whether to move the space station to avoid a possible hit was expected later Friday.