First (and only so far) was in 2019 when they beat the Houston Astros in game 7 of the World Series.
Eight teams haven't won the World Series: the Padres, Rangers, Rays, Rockies, Astros, Brewers, Mariners and Nationals (formely the Expos). The Nationals and the Mariners have yet to even make it to the World Series.
The Washington Nationals have one 1 World series championship which was in 2019. This was the first time in franchise history. However, Washington did win the World Series in 1924 as the Washington Senators.
The Astros, Rangers, Rockies, Expos/Nationals, Brewers, Mariners, Padres, and Devil Rays have never won a World Series.
The Seattle Mariners and Washington Nationals have both never been to the World Series, so they have none. In addition, the Rockies, Rangers, Padres, Brewers, Rays, Astros have never won a World Series
The San Diego Padres, Tampa Bay Rays, Washington Nationals, Texas Rangers, Houston Astros, Colorado Rockies, Milwaukee Brewers, and Seattle Mariners are MLB teams that have never won a series. The Nationals and Mariners have never appeared in the Series.
The Seattle Mariners is one of two major league baseball franchises that have never appeared in a World Series. The Washington Nationals in the other.
never because they were the Montreal expos but funds got cut from the team and the players split up then the nationals took their spot.
Teams that have never won a World Series: Colorado Rockies, Houston Astros, Milwaukee Brewers, Tampa Bay Rays, Seattle Mariners, Texas Rangers, Washington Nationals.