The NFL owners unanimously voted in favour of their takeover of the club, which was confirmed on Friday in an announcement by the team.
They wrote in a letter to Buffalo's supporters: "Today marks a historic day both for our family and for the city we love. As the new owners of the Buffalo Bills, it's with great privilege that we can say to all the fans: The Bills are here to stay.
"We are grateful to Ralph Wilson for choosing Buffalo 54 years ago and we look forward to continuing the Buffalo Bills legacy. We are truly honoured to represent this team and everything it stands for and are dedicated to sustaining the long-term success of this franchise.
"Our family continues to be inspired by the work ethic, loyalty and character of those who live in this great region. We understand the commitment needed to meet the level of dedication fans have shown this team. A new chapter begins today for both the city and our family."
The Pegulas also own NHL side the Buffalo Sabres.