Harrison will earn $1 million with $250,000 in incentives next season, a source told The Athletic's Ken Rosenthal.
Harrison appeared in 33 games for the Nationals this past season. They signed him in July following his release from the Philadelphia Phillies.
The 33-year-old produced a .278/.352/.418 slash line with 22 hits and 14 RBIs in 91 plate appearances for Washington. He provides the Nationals with defensive versatility, having appeared at six different positions throughout his career.
The two-time All-Star has played 10 seasons in the big leagues, spending time with the Nationals, Phillies, Pittsburgh Pirates, and Detroit Tigers.