General Manager Doug Whaley made the announcement Friday during the team's pre-draft luncheon. The Bills faced a deadline next week to determine whether to lock in the player through the 2015 season.
Dareus, who's started since arriving at Buffalo as the fourth pick in 2011, had a career-best 7-1/2 sacks last year.
However, Dareus ran into trouble with first-year coach Doug Marrone last season. He was held out from starting each of the Bills' final two games for violating a team rule.
He also appeared in his first Pro Bowl after filling in for injured San Francisco 49ers lineman Justin Smith.
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