Johnson then will move into a role as a consultant to the club in 2014. The Nationals announced the arrangement Saturday.
At 70 years old, Johnson will be the oldest manager in the majors in 2013.
Last season, he led the Nationals to their first NL East title and a majors-high 98 wins. Washington lost to the St. Louis Cardinals in an NL division series, blowing a 6-0 lead in Game 5.
Johnson is one of three finalists for the NL manager of the year award. The winner will be announced Tuesday.