The franchise began in 1969 as the Montreal Expos, the first major league team based outside the United States, and spent most of its 36 seasons in Canada as a competitive but often overlooked club. Its best teams included a 1981 division title in a strike-shortened season and a 1994 squad with the best record in baseball when a players' strike wiped out the rest of that season and the playoffs. Chronic financial difficulties and declining attendance eventually led Major League Baseball itself to take ownership of the team, and after a prolonged relocation search, the franchise moved to Washington, D.C., for the 2005 season and was renamed the Nationals.

The early Washington years were difficult, but a deliberate rebuilding approach that landed top draft picks Stephen Strasburg and Bryce Harper laid the groundwork for sustained success, including four division titles between 2012 and 2017, each ending in an early postseason exit. The franchise finally broke through in 2019, winning the World Series as a wild-card entrant behind pitchers Max Scherzer and Stephen Strasburg. The team was quickly dismantled afterward through trades of stars such as Scherzer, Trea Turner, and Juan Soto, and it has spent the first half of the 2020s in a rebuilding phase under new front-office leadership while remaining under the ownership of the Lerner family, who have at times explored but ultimately not completed a sale of the club.