Johnson was suspended four games for violating the NFL policy on performance-enhancing substances.
Johnson, 31, is a former third-round pick of the Panthers back in 2007. He returned to the Panthers this past March on a two-year, $8 million contract that included $2.5 million guaranteed.
Johnson stands to make a base salary of $1 million for the 2017 season to go along with $2.25 million in 2018 and a $1 million roster bonus.
In 2017, Johnson has appeared in 11 games for the Panthers and recorded 16 tackles, no sacks and a pass defense.