Considered one of California's fastest players, he helped lead West Covina to the CIF Southern Section Division VII championship and a 11-2-1.

[8] On October 24, 2011, Thurmond was placed on injured reserve with a broken fibula and high ankle sprain, ending his season.

Thurmond began the 2013 NFL season serving a four-game suspension then returned to replace Brandon Browner who had lost trail speed and was less effective in slot coverage.

The Seahawks' secondary would ultimately thrive in 2013 with him, Brandon Browner, Richard Sherman, Kam Chancellor, Earl Thomas, and Byron Maxwell all excelling together as the Legion of Boom.

Thurmond defended the slot throughout the season and stepped in for the suspended Browner in the postseason to help the Seahawks franchise win its first Super Bowl, defeating the Denver Broncos, 43–8.

[11][12] On September 15, 2014, Thurmond was placed on injured reserve after a torn pectoral sustained in a Week 2 game against the Arizona Cardinals.

Thurmond had his best year statistically, with 71 tackles, 3 interceptions, 7 pass deflections, 2 sacks, 2 forced fumbles, and 1 safety, all career highs.