Southwest Airlines has launched a new interline partnership with Singapore Airlines, significantly expanding its international connectivity and giving customers access to more than 130 destinations worldwide. The agreement was announced on June 8 during the International Air Transport Association ( IATA) Annual General Meeting in Rio de Janeiro, Brazil. Through the partnership, travelers can now book seamless itineraries connecting Southwest’s domestic network with Singapore Airlines’ extensive global route system via Los Angeles, San Francisco, and Seattle.

The deal represents another major milestone in Southwest’s evolving international strategy. Long known for its predominantly domestic focus, the Dallas-based carrier has spent the past year rapidly building relationships with foreign airlines to provide customers with greater access to international destinations without operating long-haul flights itself.

More Than 130 Destinations Now Reachable Through A Single Connection

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Southwest stated that the partnership initially allows customers to purchase combined itineraries through Singapore Airlines’ website, with plans to expand booking options in the future. Passengers arriving on Singapore Airlines flights at Los Angeles International Airport (LAX), San Francisco International Airport (SFO), and Seattle-Tacoma International Airport (SEA) can connect onto Southwest’s extensive domestic network across the United States.

The agreement provides access to Singapore Airlines’ extensive network of over a hundred destinations across Asia, Europe, Africa, Australia, and the South Pacific. At the same time, international travelers arriving on Singapore Airlines can connect to dozens of Southwest-served destinations that are not currently served by many other international carriers. The partnership creates new travel opportunities for both leisure and business passengers while strengthening connectivity between North America and Asia.

Andrew Watterson, Southwest Airlines Chief Operating Officer, posted on LinkedIn:

“With this new agreement, Customers can access one‑ticket journeys between the US and Singapore, connecting seamlessly between our network and Singapore Airlines’ global operation.”

Southwest’s Growing Portfolio Of International Airline Partners

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The Singapore Airlines agreement is Southwest’s eighth interline partnership. The carrier’s current portfolio of airline partners now includes All Nippon Airways, China Airlines, Condor, EVA Air, Icelandair, Philippine Airlines, Turkish Airlines, and Singapore Airlines. These agreements collectively allow Southwest to offer significantly broader international travel options than ever before.

Notably, Singapore Airlines is Southwest’s fourth new international airline partnership announced within the past year. The carrier previously launched new interline relationships with China Airlines, ANA, and Condor as part of a wider strategy to transform its international connectivity. The rapid pace of partnership announcements highlights Southwest’s commitment to expanding beyond its traditional point-to-point domestic model.

But what is interlining, and is it the same as a codeshare? Interlining differs from a traditional codeshare agreement. Under an interline arrangement, airlines coordinate passenger itineraries and checked baggage across multiple carriers, allowing travelers to complete journeys on a single ticket while flying with more than one airline. A codeshare involves a deeper level of cooperation, with one airline placing its flight code on services operated by another carrier and selling seats directly on those flights.

Southwest has indicated that it is actively pursuing additional partnerships with international airlines for both transpacific and transatlantic travel. If more agreements are announced, the carrier’s global reach could continue expanding rapidly without requiring Southwest to operate its own long-haul international fleet.

The Fourth Major International Partnership In Just One Year

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The announcement comes during a period of significant change for Southwest Airlines. In recent years, the carrier has been pursuing new revenue opportunities and network enhancements while facing increased competition from both domestic and international airlines. Expanding partnerships with global carriers allows Southwest to offer customers a more comprehensive travel product while remaining focused on its core domestic operations.

For Singapore Airlines, the agreement provides enhanced access to hundreds of daily Southwest departures throughout the United States. The partnership is particularly valuable because Southwest serves numerous secondary cities and leisure destinations that may not be easily accessible through other airline partnerships. This broadens Singapore Airlines’ reach within the US market and strengthens its competitive position against rival global carriers.

The two airlines indicated that additional enhancements to the partnership may be introduced over time. As Southwest continues developing its interline strategy, travelers can expect more opportunities to combine domestic and international travel on a single itinerary, creating a more straightforward passenger experience across multiple continents.