The 32-year-old hit .259 with a club-high 11 pinch hits last season, his first in Washington. He made 42 starts and played in 105 games for the NL East champions, appearing in left field and at every infield position but shortstop.
Frandsen has the same performance bonuses in Friday's deal that were in his 2014 contract: $50,000 each for 225, 300, 350 and 400 plate appearances and $100,000 for 450. He had 236 this year.
Ten Nationals remain eligible for arbitration: pitchers Stephen Strasburg, Doug Fister, Tyler Clippard, Drew Storen, Craig Stammen, Jerry Blevins and Ross Detwiler; infielder Danny Espinosa; and catchers Wilson Ramos and Jose Lobaton.