The 30-year-old left-hander is poised to become Washington's closer in his 11th major league season, joining the back end of the bullpen that already includes Will Harris, Daniel Hudson and Tanner Rainey.
Hand had another solid season as the closer for the Cleveland Indians in 2020, leading the major leagues with 16 saves, but he was a victim of the team's salary purge heading into 2021. Cleveland declined his $10 million option in exchange for a $1 million buyout.
Cleveland tried to deal the three-time All-Star after the season but was unable to find a trade partner.
Hand was acquired from the San Diego Padres at the trade deadline in 2018. In two-plus seasons with Cleveland, he had 58 saves in 65 chances and a 2.78 ERA and 154 strikeouts in 107 innings over 111 games.
Hand went 2-1 with a 2.05 ERA and was 16-for-16 in save chances during the pandemic-shortened, 60-game 2020 season. However, his blown save against the New York Yankees led to the Indians' elimination in the American League Wild Card Series.
The Padres claimed Hand off waivers from Miami early in the 2016 season. Known for his slider, he has 105 saves in 128 chances, with a 3.65 ERA and 624 strikeouts in 608⅔ innings. His fastball velocity has dropped over 2 mph the past two seasons and averaged 91.4 mph in 2020.
After tying for last place in the National League East in 2020, the Nationals have acquired Hand, starter Jon Lester (pending a physical), slugger Kyle Schwarber and first baseman Josh Bell. They also brought back the organization's longest-tenured player, Ryan Zimmerman, after he opted out in 2020.
The Associated Press contributed to this report.