Southwestern Energy was an independent natural gas and oil exploration and production company based in Spring, Texas. Founded in 1929 as Arkansas Western Gas Company, it focused on the exploration, development, and production of natural gas, natural gas liquids (NGLs), and crude oil. The company operated primarily in the Appalachian Basin and the Haynesville Shale, controlling significant acreage, including over 2.5 million net undeveloped acres in New Brunswick, Canada.

The company provided a range of services, including hydraulic fracturing, drilling, water management, and commercial asset management. It marketed and transported natural gas, NGLs, and oil to major utilities, energy companies, and LNG exporters. As of the end of 2023, natural gas made up about 77% of its proved reserves, with NGLs and petroleum comprising 20% and 3%, respectively. In October 2024, Southwestern Energy merged into Expand Energy, becoming part of the largest natural gas producer in the U.S.