Coleman, who will turn 30 in July, was scheduled to count $5,150,000 against the 2018 salary cap. Releasing him cleared $2.65 million in cap space.
Releasing the 31-year-old Johnson, who signed a two-year extension last year worth $9.5 million, cleared another $3.25 million in space.
Coleman in 2016 signed a three-year extension worth $17 million with $7 million guaranteed. He originally joined the Panthers as a free agent in 2015, leading the team with seven interceptions. He had only four interceptions in 2016 and none this past season when he was named a team captain for the first time.
Johnson was suspended four games this past season for violating the league's policy on performance-enhancing drugs. He was inactive for the playoff game against New Orleans for an unspecified reason.
Johnson's 67.5 sacks rank second on the team's all-time list behind defensive end Julius Peppers, 38, who has yet to announce he is coming back for another season but reportedly is leaning toward a return.
Johnson didn't have a sack this past season, the first time that has happened since his rookie year of 2007, when he played in only two games as a third-round pick out of Georgia. He's had five sacks the past three seasons after having 8.5 in 2014 and 11.0 in 2013.
Carolina had just shy of $20 million in salary-cap space before the releases.