No injuries were reported.
A Southwest spokesman said there were reports of smoke in the cabin and a flight attendant having trouble breathing.
Passengers were reportedly using oxygen masks inside the cabin.
The crew made the decision to divert the flight and landed without incident at MacArthur Airport, the airline spokesman said.
It is not clear what caused the smokey conditions.
Southwest will replace the aircraft and continue the flight to Orlando. Passengers should expect about a two-hour delay.
For more information please call Southwest Airlines at 1-800-435-9792.