The airline said late Thursday that the contract would run through May 2019 and includes pay raises, possible bonuses and changes in work rules. The union said the deal would keep Southwest's flight attendants the highest-paid in the industry.
Details were not disclosed. Contract talks have lasted longer than two years.
Dallas-based Southwest Airlines Co. had 11,850 flight attendants as of last Dec. 31, according to a regulatory filing.
The flight attendants are represented by the Transport Workers Union. Southwest says they'll get details of the agreement in the coming weeks and hold a ratification vote.