The Alabama State Troopers released a statement saying Dareus was arrested Monday night on charges of possession of a controlled substance and possession of drug paraphernalia.
Dareus was stopped for speeding, and the controlled substance charge is a felony, according to the statement.
"All we know right now is what we have seen in media reports, and we will continue to look into this," Bills senior vice president of communications Scott Berchtold told ESPN.com.
Dareus was selected third overall in the 2011 draft and is entering his fourth season with the Bills. The 24-year-old played at Alabama.
Last season, he had 7.5 sacks and 71 tackles and appeared in his first Pro Bowl.
The Bills exercised the fifth-year option on his contract in April. 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.
ESPN.com's Mike Rodak and The Associated Press contributed to this report.