WAS Nationals

With contraction no longer an option in the immediate term, MLB began looking for a new site for the Expos. Some of the choices included Oklahoma City; Washington, D.C.; San Juan, Puerto Rico; Monterrey, Mexico; Portland, Oregon; Northern Virginia (such as Arlington or Dulles); Norfolk, Virginia; Las Vegas; and Charlotte, North Carolina. Washington, D.C., and both Virginia locations emerged as the front-runners.

On September 29, 2004, MLB announced that the Expos would move to Washington, D.C., for the 2005 season, returning professional baseball to the United States's capital. On November 15, arbitrators struck down a lawsuit former team owners brought against MLB and former majority owner Jeffrey Loria, bringing to an end all legal actions that could have impeded a move. The other MLB team owners approved the move to Washington, D.C., in a 28–1 vote on December 3 (Baltimore Orioles owner Peter Angelos cast the sole dissenting vote).

Although there was some sentiment to revive the name Senators when the Expos moved to Washington in 2005, legal and political considerations factored into the choice of Nationals, a revival of the first American League franchise's official name used from 1901 to 1956. Politicians and others in the District of Columbia objected to the name Senators because the District of Columbia does not have voting representation in Congress. In addition, the Rangers still owned the rights to the Senators name.

Washington, D.C., mayor Anthony A. Williams supported the name "Washington Grays" in honor of the Negro-league team Homestead Grays (1929–1950), which had been based in Pittsburgh but played most of their home games in Washington's Griffith Stadium during much of the 1940s. On November 21, 2004, the team's management chose the name "Washington Nationals", revealing the club's official colors of red, white, and blue the next day. The team would begin their tenure in DC at RFK Stadium, while planning a move to a new, purpose built stadium which was under construction.

The Nationals played their first game on April 4, 2005, at Citizens Bank Park in South Philadelphia, losing to the Philadelphia Phillies 8–4. The Nationals finished their inaugural season at .500 with an 81–81 record. Its first draft pick as the Nationals was Virginia native and University of Virginia graduate Ryan Zimmerman in the first round of the 2005 draft. Zimmerman made his MLB debut in 2005 and became one of the team's best players and the face of the franchise, playing his entire career with the Nationals.^[]

When Ted Lerner took over the club in mid-2006, he hired Stan Kasten as team president. Kasten was widely known as the Atlanta Braves' architect before and during their run of 14 division titles. Kasten was also the General Manager or president of many other Atlanta-area sports teams, including the Atlanta Hawks and Atlanta Thrashers. "The Plan", as it became known, was a long-range rebuilding and restructuring of the team from the ground up. This plan included investing in the farm system and the draft to build a team suitable for their new stadium.^[]

In the front office, the Nationals hired well-respected former Arizona scouting director Mike Rizzo to be the Vice President of Baseball Operations, second in charge under then-general manager Jim Bowden. Rizzo would take over as the National's general manager in 2009.

For the 2008 season, the Nationals moved to their new stadium, dubbed Nationals Park. The Nationals played their first home game there on March 30, 2008. ESPN televised the game nationally, for which U.S. President George W. Bush threw out the first pitch. Ryan Zimmerman hit his fifth career walk-off home run to give the Nationals a win in the first game in their new stadium.

The Nationals finished in last place in four out of five years from 2006 to 2010, but began building the foundations of a contender with their first-overall draft picks of pitcher Stephen Strasburg (in 2009) and catcher Bryce Harper, whom the team converted to the outfield, (in 2010), as well as their sixth-overall draft pick of infielder Anthony Rendon (in 2011). Strasburg, one of the most anticipated prospects in baseball history, struck out 14 batters in his 2010 Major League debut at home against the Pittsburgh Pirates.

In 2011, the Nationals signed Jayson Werth to the team's first big free-agent contract. With a mix of homegrown players and players acquired via trade and free agency, the Nationals clinched their first playoff berth and first division title in 2012. Teenage phenom Harper was named NL Rookie of the Year, the youngest ever to win. The Nationals were knocked out of the 2012 NLDS by the St. Louis Cardinals in five games after the Cardinals took the lead with two outs in the top of the ninth of game 5. After missing the playoffs in 2013, they hired Matt Williams as manager and rebounded to win their second division title in 2014, but were eliminated in the 2014 NLDS by the San Francisco Giants. In 2014, they acquired shortstop prospect Trea Turner in a trade with the San Diego Padres, with Turner eventually becoming a major part of the Nationals' core.

In 2015, the Nationals signed top free agent pitcher Max Scherzer to a 7-year, $210 million contract. That year, Harper had one of the greatest offensive seasons in MLB history, becoming the youngest player to win the NL MVP unanimously. Despite strong individual showings, the Nationals missed the playoffs, leading to Williams' firing. The team hired veteran manager Dusty Baker in 2016, and returned to the playoffs only to be eliminated by the Los Angeles Dodgers in the 2016 NLDS in five games. They won the NL East title in 2017, but were eliminated in the NLDS yet again after losing game 5 to the Chicago Cubs. Baker's contract was not renewed after the 2017 playoff loss, and the team hired Dave Martinez as their sixth manager in ten years.

In 2018, the All-Star Game was played at Nationals Park. 19-year-old phenom Juan Soto had an exceptional debut campaign, finishing 2nd in NL Rookie of the Year Voting. The Nationals failed to make the playoffs in 2018, finishing a disappointing second in a year they were expected to sail to the playoffs. After the 2018 season, superstar slugger Bryce Harper left the team via free agency, signing with the rival Philadelphia Phillies.

The Nationals began the 2019 season with a record of 19–31, with their projected chances of winning the World Series at that time being 1.5 percent. They then posted a 74–38 record over the remaining 112 games, finishing with an overall record of 93-69 and earning a spot in the 2019 National League Wild Card Game, which they won over the Milwaukee Brewers 4–3. In the NLDS, the Nationals defeated the Los Angeles Dodgers in five games, propelling them past the divisional round for the first time in franchise history. The Nationals then swept the St. Louis Cardinals in the NLCS, giving them their first NL pennant. The team then defeated the Houston Astros in game seven of the 2019 World Series, giving them their first World Series championship, with Strasburg being voted series MVP. The World Series was the first in MLB history that saw no team win a game at home, as the road team won all seven. The Nationals went a perfect 5–0 in elimination games during the playoffs, all of which were come-from-behind victories, the first team in MLB history to do so.

Franchise cornerstone Anthony Rendon left in free agency for the Los Angeles Angels after the 2019 season. The Nationals agreed to re-sign fellow building block Stephen Strasburg to a massive seven-year deal that guaranteed him $245 million. However, injuries limited him to just 31 and 1/3 innings under the contract, and eventually forced him to retire in 2024. The Nationals struggled in 2020, when the coronavirus pandemic led to the season being shortened to 60 games; the team finished 26-34 and missed the playoffs. After another disappointing start to the 2021 season, in which the team was under .500 at the trade deadline, GM Mike Rizzo disassembled much of the team, trading ace pitcher Max Scherzer and superstar shortstop Trea Turner to the Dodgers, among many other trades of starting players in exchange for prospects, signifying the start of a rebuilding process. Ryan Zimmerman, the longtime face of the franchise who had been with the team since its inaugural 2005 season, announced his retirement after the 2021 season, marking the end of the first era of Nationals baseball.

On August 2, 2022, the Nationals sent 23-year-old superstar Juan Soto to the San Diego Padres in a blockbuster trade after he turned down a 15-year, $440 million contract extension offer, which would have constituted the richest contract in baseball history. In doing so, the Nationals lost its franchise icon and one of the last integral players from the 2019 championship team. The Nationals received one of the largest prospect hauls in any single trade in baseball history in return, with the front office hoping that the elite prospects would form the core of the next championship team. After trading Soto and others, the Nationals finished the 2022 season with the worst record in baseball at 55–107.

In 2022, The Washington Post reported that the Lerner family was exploring a restructuring of the team's ownership, including the possibility of selling the team outright. Ted Lerner died prior to the 2023 season from pneumonia complications; his son Mark had become the public-facing principal owner in 2018, though Ted had retained his full interest in the team's decisions.

The Nationals would begin to bounce back after 2022, as young players such as CJ Abrams and Josiah Gray led them to an improvement of 16 wins in 2023, finishing at 71–91. Additionally, the rebuild had strengthened a once-weak group of prospects. ESPN's annual farm system ranking showed improvement from 30th entering 2021 to 22nd in 2022, 13th in 2023, and 16th in 2024.

The Nationals ended the 2024 season with the same record as 2023 at 71–91. However, the rebuild progressed with top prospects James Wood, acquired via the Soto trade, and Dylan Crews, drafted #2 overall in 2023, making their debuts. Additionally, shortstop CJ Abrams, also acquired via the Soto trade, was selected to the 2024 All-Star Game. On July 6, 2025, following a disappointing first half of the 2025 season below internal projections for the rebuild, the Nationals fired Martinez as their manager, and fired Mike Rizzo as general manager, who had held the role of general manager since 2009 and had been the president of baseball operations since 2013. Miguel Cairo and Mike DeBartolo were respectively named as the interim replacements for manager and general manager.