The deal was first reported Tuesday by NFL Network.
Bynes, who turns 31 on Aug. 24, was one of the biggest surprises on defense for the Ravens last season. After being out of football for training camp and the first quarter of the regular season, Bynes reunited with Baltimore in Week 5 and immediately anchored the middle of a then-struggling defense for the final three months of the regular season.
Over the final 12 games, Bynes recorded the third-most tackles (45) for the Ravens' defense, which allowed the fewest yards (268.9) and points (15.1) over that span.
This was the second stint in Baltimore for Bynes, who played his first three seasons with the Ravens after going undrafted.
The Ravens are expected to draft an inside linebacker and could do so as early as the first round. Baltimore has been linked to Oklahoma's Kenneth Murray and LSU's Patrick Queen with the No. 28 overall pick. The current inside linebackers on the Ravens' roster are L.J. Fort, Chris Board and Otaro Alaka.