One of the plane's engines was shut down during the emergency Monday, WRAL-TV, Raleigh, N.C., reported.
The plane carried 124 passengers and five crew members, officials said.
The flight, which took off just before 6 p.m., was destined for Chicago but returned 30 minutes after takeoff, the broadcaster said.
Passenger Shelly Tranchita described the sound of the engine after it hit the bird as "wha womp, wha womp."
"It was like a pinwheel, and you heard it hitting things," she said.
"We saw some smoke and it is very, very scary. Nobody was saying anything. Nobody knew what was going on. Everyone was calm. People were in tears, people were scared, babies were crying -- but we had to pray to God for a safe landing.
When the plane landed, the occupants broke into applause, Tranchita said.
Southwest provided another plane for the passengers to travel to Chicago later in the evening, WRAL said.
Britney Spears debuts 'Perfume' video
Wisconsin business offering 'therapeutic cuddling' forced to close