After an offseason stint with the Seattle Seahawks, he played in mostly reserve roles for the Minnesota Vikings in 2017 and the Denver Broncos in 2018.

In 2019, he returned to a starting role playing for the Arizona Cardinals, which continued after he was claimed off waivers by the Tennessee Titans partway in the season.

[1] Brock spent his freshman and sophomore years playing safety for Mississippi Gulf Coast Community College.

[3] In 2009, Brock transferred to Belhaven University of the National Association of Intercollegiate Athletics (NAIA) to finish out his senior year.

Brock signed as an undrafted free agent by Buffalo Bills after going unselected in the 2010 NFL draft on April 26, 2010.

Brock made his NFL debut against the Denver Broncos and that year only played in three games and recorded only four tackles for the 49ers.

[9] When Tarell Brown went down with a rib contusion in a Week 11 loss against the New Orleans Saints, Brock took over as duties as starting cornerback.

Brock was a key part of a memorable play in Week 16, on Monday Night Football against the Atlanta Falcons.

He struggled with a toe injury throughout the majority of the season that he sustained in a Week 1 victory over the Dallas Cowboys and ended up only playing 3 games and recording 7 tackles.

Without the presence of their number 1 corner, the 49ers struggled to find a consistent replacement to take over the nickel duties as they now moved Perrish Cox out of that position to fill Brock's role.

As the second quarter was about to end, Manning tried to throw a touchdown to Beckham, but Brock's tight coverage gave him the interception.

During Week 8 of the 2015 Season, Brock picked off quarterback Russell Wilson during the end of the second quarter to tie cornerback Kenneth Acker with the most interceptions on his team.

In 2016, Brock started all 16 games for the first time in his career and finished the season with 59 combined tackles, 14 passes defended, an interception, and 1 forced fumble.

During Week 16 against the Los Angeles Rams, Brock intercepted Jared Goff and returned it 39 yards as the 49ers narrowly won 22–21.

On August 16, 2017, after his domestic violence case was dismissed, Brock signed with the Seattle Seahawks on a one-year deal.

[15] He was named a starting cornerback opposite rookie Byron Murphy to begin the season in place of the suspended Patrick Peterson.

[22] On April 7, 2017, Brock was arrested in Santa Clara County, California following an alleged incident which left his children's mother with visible injuries.