The team announced Friday it had released the former ninth overall pick by Jacksonville, along with receiver Victor James.
Seattle has now signed six of its nine draft picks.
Williams starred at the University of Washington and signed with the Seahawks following a free-agent tryout in April. Seattle coach Pete Carroll recruited Williams out of Lakes High School in Tacoma, Wash., while Carroll was coaching at USC.
Williams is serving two years of probation stemming from a cocaine possession charge from a May 2009 incident in Houston. An off-duty police officer used a Taser on Williams when he allegedly refused to leave a bar.
He has been out of the league for a year. Yet the 27-year-old said upon signing with the Seahawks he was a better man. He'd gotten engaged, and he has an infant son. He seemed poised to provide Seattle the big receiving target it has lacked outside for years.
"I'm just glad I have the opportunity to be out here and playing. It means everything for me and from my family," he said after one of his first practices with the Seahawks.
But then Mike Williams, another former top 10 overall pick also making a comeback with the Seahawks, began impressing during minicamps. Mike Williams played for Carroll at USC, before problems with weight and inconsistency caused the Lions, Titans and Raiders to give up on him.
Plus, Carroll declared this week that T.J. Houshmandzadeh and Deion Branch would be ready for the start of training camp at the end of July. Seattle's top returning veteran receivers have been recuperating from offseason surgeries. Houshmandzadeh's was for a hernia. Branch, a former Super Bowl MVP, had his third knee surgery in two years.
Their progress made Reggie Williams expendable at what is perhaps the Seahawks' most stocked position.