The deal is worth $3.5 million and could reach as much as $12 million total with incentives.
Johnson, a two-time Pro Bowl pick who has run for 6,219 yards and 55 touchdowns in eight NFL seasons with the Kansas City Chiefs and Cincinnati Bengals, is expected to work with incumbent Redskins running back Clinton Portis.
Johnson also has 154 catches for 1,373 yards and six TDs.
Redskins coach Mike Shanahan called the 6-foot-1, 230-pound Johnson a "physical runner" and a "great addition to our backfield."
During his visit to Washington this week, Johnson said he envisioned himself and Portis being for the Redskins what he and Priest Holmes once were for the Chiefs.
Shanahan and general manager Bruce Allen have said Portis will
be the team's running back next season, but Portis ended last year
on injured reserve with a concussion. He ran for a career-low 494
yards and didn't have the burst of speed from earlier in his
The flamboyant Portis hasn't shied from publicly criticizing
coaches and teammates in years past, and he has not been a fan of
the team's offseason workout program.
On Thursday, Shanahan guaranteed that Portis will be in
attendance when the offseason workouts begin Monday. With Johnson
and Portis both on the roster, the Redskins have insurance in case
one or the other misbehaves or is unproductive.
"Competition is a great motivator," Johnson's agent, Peter Schaffer, said Friday.
Schaffer said Johnson was also motivated to return to the Washington area, where he grew up as a Redskins fan.
The Redskins have taken a different approach to free agency
under Shanahan. Johnson is the fourth player signed in eight days,
but none of the contracts have been blockbusters - and he's by far
the biggest name added to date.
"We are excited to bring in a running back that has had so much
success in this league," Shanahan said in a statement released by
the team. "Larry is a physical runner who will be a great addition
to our backfield."
Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.