The deal, contingent on Lind passing a physical, provides the Nationals with depth both in the outfield and at first base.
The 33-year-old Lind clubbed 20 home runs and had 58 RBIs in 126 games with the Seattle Mariners in 2016. It marked the sixth time in his career that Lind hit at least 20 homers.
A third-round draft pick of Toronto in 2004, Lind spent his first nine seasons with the Blue Jays, establishing career highs in 2009 with 35 homers, 114 RBIs and a .305 batting average.
Lind appeared in just 96 games with Toronto in 2014 and was traded after the season to Milwaukee, where he batted .277 with 20 homers and 77 RBIs. The Brewers dealt Lind to Seattle in December 2015.
In 11 major league seasons, Lind sports a .271 career batting average with 186 home runs and 664 RBIs.