Johnson previously played for new Cowboys passing game coordinator Kris Richard while they were together in Seattle.
Dallas is clearly in the market for safety and have reportedly signed S Dominick Sanders to a contract.
Johnson, 30, wound up signing on with the Seahawks as an undrafted free agent out of Boise State back in 2011. He spent four years in Seattle before signing a two-year, $2.5 million with the Redskins in 2015.
Washington released Johnson after one year and he had brief stints with the Chiefs and Seahawks before signed on with the Jaguars in August of last year. Unfortunately, Johnson was cut a few weeks later and sat out the 2017 season.
In 2016, Johnson appeared in four games and recorded five tackles and no interceptions.