The Patriots also released three players -- cornerback Chimdi Chekwa, who signed with the team on March 12, linebacker Cameron Gordon and former Michigan quarterback Devin Gardner, who signed with the club as an undrafted free agent earlier this month.
Spikes played for the Patriots from 2010 to 2013 before signing a one-year deal with the Bills in 2014. His departure from New England included some fireworks, as he was placed on season-ending injured reserve in the playoffs and questioned the team's decision to do so.
ESPN NFL Insider Chris Mortensen had reported that the Patriots and Spikes mutually agreed to the IR designation as opposed to an outright release after the linebacker was late to a team meeting that week. That essentially ended any chance Spikes would return in 2014, with the hard-hitting outspoken linebacker saying he was happy to move on to "somewhere you're wanted."
One year later, circumstances have changed.
Spikes was a free agent once again and no longer viewed as an ideal fit in Buffalo, which is changing schemes under first-year head coach Rex Ryan. Meanwhile, the Patriots have been looking for experienced linebacker depth as starters Jerod Mayo (patellar tendon) and Dont'a Hightower (labrum) continue to rehabilitate.
The 6-foot-2, 255-pound Spikes, who is considered a strong player against the run but a liability at times in the passing game, has played 67 career regular-season games and has been credited with 340 tackles.
ESPN's Field Yates and Adam Schefter contributed to this report.