Williams was selected by the
Buffalo Bills as the second pick of the second round (no. 34 overall) in the
2011 NFL draft. Following an up and down first two seasons at
cornerback, Williams was moved to
safety for the
2013 season. On March 5, 2014, Williams signed a four-year, $26 million extension with the Bills. In 2015, Williams was injured in a Week 2 game against the
New England Patriots while attempting a flying goal line tackle on
Julian Edelman. He was completely motionless on the turf, and was taken off the field in an ambulance. Early reports stated he suffered a neck injury. In 2016, during a Week 3 game against the
Arizona Cardinals, Williams scored his first NFL touchdown, returning a botched field goal attempt for the score. In Week 7, Williams suffered another serious neck injury after a hit by
Miami Dolphins wide receiver Jarvis Landry. He was placed on injured reserve on November 1, 2016, effectively ending his season. On March 9, 2017, Williams was released by the Bills. On January 31, 2018, Williams announced his retirement from the NFL after six seasons in Buffalo. His retirement came after multiple head and neck injuries throughout his career, citing it was the main concern of other teams not signing him after workouts in 2017, including the Jaguars, Texans, and Chiefs. ==NFL career statistics==