Nationals Park is the current ballpark for the Washington Nationals of Major League Baseball, and is the first LEED-certified green stadium in the United States. The facility was opened in time for the 2008 baseball season-opening game (in North America) against the Atlanta Braves on March 30, 2008, and previously hosted collegiate baseball games. It is located along the Anacostia River in the Navy Yard/Near Southeast neighborhood of Washington, D.C. and replaces the RFK Stadium as the Nationals' home ballpark. The new ballpark, designed by HOK Sport and Devrouax & Purnell Architects and Planners, seats 41,000 fans and costs $611 million to build. It sits across the river from the D.C. United's proposed soccer-specific stadium at Poplar Point. Fans can view the Washington Monument and the U.S. Capitol building from certain areas of the stadium.

The park's name echoes the original name of the old Washington Senators ballpark, National Park, which was renamed Griffith Stadium when it was rebuilt.

Financing for the stadium was expected to be provided by a banking syndicate led by Deutsche Bank. However, finalization of the financing deal, as of December 2005, stalled due to complex negotiations among the city government, MLB as owner of the team, and the bank. The bank requested a letter of credit or comparable financial guarantee against stadium rent to cover risks such as poor attendance or terrorism. The requested guarantee was $24 million, with the city requesting that MLB provide the guarantee. The financing situation was since solved and construction began in May 2006.

The site of Nationals Park was chosen by Mayor Anthony Williams as the most viable of four possibilities for a future ballpark. The ballpark's design was released to the public at a press conference on March 14, 2006. Ground breaking was in early 2006. With an ambitious construction schedule of fewer than two years to complete the stadium, a design-build approach was selected to allow the architects and builders to work in concert with one another. Ronnie Strompf, the project superintendent, coordinates the efforts of numerous subcontractors on a daily basis.

The ballpark has 41,000 seats and features 66 suites, all around the infield. Other amenities include the "Oval Office bar." Team President Stan Kasten also said that the team might sell the naming rights to the levels of the luxury suites, which bear the names of presidents Washington, Jefferson and Lincoln. While the city has agreed to spend up to $611 million, Kasten has stated that the principal owners, the Lerner family, have spent tens of millions of dollars more on "jazzing up the park." The park has an out-of-town scoreboard installed in the right field wall. It is 102 feet long. The main scoreboard is more than 5 times bigger the one at RFK Stadium. The main scoreboard is 101 feet long and 47 feet high.

On March 13, 2007, Kasten announced that not only was the Nationals new ballpark on schedule to be ready by Opening Day 2008, but that there would be a grove of cherry blossoms located just beyond the left field bleachers. Kasten stated that the cherry blossoms will provide a look that Americans associate with the nation's capital. The Nationals also have plans to erect three statues in the ballpark, honoring Walter Johnson of the original Washington Senators, Frank Howard of the expansion Senators, and Josh Gibson of the Negro League Homestead Grays, which played many of its games in Washington.