The moves come as the Panthers claimed three other players off waivers Sunday. Carolina also released WR Torrey Smith.
Seymour, 25, is a former sixth-round pick out of USC by the Bills in the 2016 NFL Draft. He was entering the second year of a four-year, $2.44 million rookie contract and was set to make a base salary of $540,000 in 2017 when the Bills traded him to the Panthers.
Seymour spent the entire 2018 season on injured reserve for the Panthers.
In 2017, Seymour appeared in all 16 games for the Panthers and recorded 21 total tackles and four pass defenses.
Holyfield, 21, signed with the Panthers as an undrafted free agent out of Georgia. He signed a three-year, $1.755 million contract in 2019.
During his three-year career at Georgia, Holyfield rushed 215 times for 1340 yards and nine touchdowns in 27 games. He also caught seven passes for 63 yards.