Brock was released by the Arizona Cardinals on Monday after a 34-7 loss to the Los Angeles Rams on Sunday. Brock joins the Titans (7-5), a team in the playoff hunt and contending for the AFC South division title.
The Tennessee secondary lost veteran starter Malcolm Butler last month. Reserve cornerback LeShaun Sims started in place of Butler but missed last week's game due to an ankle injury. The Titans were without cornerback Adoree Jackson (knee) in the second half of their 31-17 win over the Colts this past Sunday. Rookie cornerback Kareem Orr and reserve Tye Smith both saw significant action in Jackson's place.
Tennessee's pass defense is 27th in the NFL, allowing 260.1 passing yards per game.
Brock, 31, signed a one-year contract with the Cardinals in April and started seven of the 10 games he was active for Arizona. He posted 37 tackles and three pass breakups this season.
The 10-year veteran signed with the 49ers as an undrafted free agent out of Belhaven in 2010. He also played college football at Minnesota after arriving from Mississippi Gulf Coast Community College. Brock's NFL tenure includes stops with the Seahawks, Vikings, Broncos and Cardinals.