The value of the tag for Joyner is $11.287 million for the 2018 season. The Rams, who would still like to sign Joyner to a long-term deal, have until July 16 to sign him to a multiyear contract or he will have to play the season on the franchise tag.
This marks the third straight year the Rams have placed the franchise tag on a defensive back. Cornerback Trumaine Johnson had received the tag the past two offseasons. He will be an unrestricted free agent on March 14 when the new league year begins.
The Rams' decision to franchise Joyner also means that wide receiver Sammy Watkins will be an unrestricted free agent next week. The Rams' franchise decision came down to Joyner or Watkins.
Watkins is open to returning to the Rams but also anticipates a strong market in free agency, a source told ESPN's Josina Anderson.
Because the team is using its non-exclusive tag, Joyner is free to sign an offer sheet with another team. Should the Rams choose not to match an offer sheet for Joyner, they would be due two first-round draft picks from his new team.
Joyner spent his first three seasons primarily as a slot corner for the Rams, but he excelled when given a chance to play safety under defensive coordinator Wade Phillips in 2017. Joyner earned the third-highest grade among safeties by Pro Football Focus, finishing with three interceptions -- after not recording any in the previous three years -- and 49 tackles in 12 games.
Joyner, 27, allowed a 31.8 passer rating when targeted and 0.36 yards per coverage snaps, ranked 12th among 59 safeties, according to Pro Football Focus. He was one of only two safeties to not miss a tackle in the passing game, and he also covered slot receivers when needed.
Joyner is an aggressive hitter with great ball skills. He was selected in the second round of the 2014 draft after a standout stint as a safety at Florida State, but he played only in sub-packages with the Rams while under Jeff Fisher.
ESPN's Alden Gonzalez contributed to this report.