Jacksonville also signed S Doug Middleton to the practice squad and released DB Jordan Brown.
Gilchrist, 30, is a former second-round pick of the Chargers back in 2011. After four years San Diego, Gilchrist signed a four-year, $22 million contract with $8.5 million guaranteed with the Jets in 2015.
Gilchrist was set to make a base salary of $6 million for the 2017 season when the Jets elected to designate him as a post-June 1 release in 2017. It took until August for him to sign a one-year contract with the Texans.
Gilchrist signed a one-year, $4 million deal with the Raiders for the 2018 season and played out his contract. The Lions signed him to a contract in October before releasing him after only a few days.
In 2018, Gilchrist appeared in all 16 games for the Raiders and recorded 58 tackles, three interceptions and six pass defenses. Pro Football Focus had him rated as the No. 82 safety out of 90 qualifying players.