Parker's father, Ronzo, was a truck driver and his mother Rose worked at a Montessori public school.
[10] Head coach Pete Carroll named Parker the sixth cornerback on the depth chart, behind Richard Sherman, Brandon Browner, Byron Maxwell, Roy Lewis, and Kennard Cox.
Throughout training camp in 2012, Parker competed for a roster spot as a backup cornerback against Roy Lewis, Phillip Adams, Jeremy Lane, and Coye Francies.
[14][15] On October 17, Parker was promoted to the active roster to replace an injured Kenny Onatolu, then later released and signed to the practice squad on November 7.
[5] Throughout training camp, Parker competed for a roster spot as a backup cornerback against DeShawn Shead, Will Blackmon, Byron Maxwell, Tharold Simon, and Walter Thurmond.
[21] Head coach Andy Reid named Parker the fifth cornerback on the depth chart to start the regular season, behind Sean Smith, Brandon Flowers, Dunta Robinson, and Marcus Cooper.
He finished the 2013 NFL season with 17 solo tackles, three pass deflections, two interceptions and one sack, playing in 16 games and starting in one.
[25] The Kansas City Chiefs finished the 2013 NFL season as second in the AFC West with an 11–5 record and earned a Wild Card berth.
Throughout training camp, Parker competed to be a starting cornerback against Sean Smith, Marcus Cooper, and Phillip Gaines.
[27] In the Kansas City Chiefs' season-opener against the Tennessee Titans, he recorded six solo tackles and broke up a pass in their 26-10 loss.
[28] Parker was moved to strong safety for the last five games of the regular season, after Eric Berry was diagnosed with Hodgkin's lymphoma.
[29] He finished the 2014 NFL season with a career-high 94 combined tackles (81 solo), 12 pass deflections, one interception, one sack, and a forced fumble, playing in 16 games with 15 starts.
[34] In the 2016 season, Parker started all 16 games for the Chiefs at safety again, recording 61 tackles, 12 passes defensed, two forced fumbles, and an interception.
On March 12, 2018, after refusing to take a pay cut for the team to make cap space, Parker was released by the Chiefs after five seasons.
On October 21, Parker scored his first NFL touchdown after intercepting a pass from Cincinnati Bengals quarterback Andy Dalton and returning it 33 yards.