Aaron Wilson of the Houston Chronicle reported the news.
It is unclear why Ihedigbo was suspended. Four-game suspensions typically coincide with a first violation of the league's policy on performance-enhancing drugs but could also signal a violation of the substance abuse policy.
Ihedigbo, 33, played four games for the Buffalo Bills in 2016.
He recorded 16 tackles, starting three of his four appearances after being signed in November. The Bills placed him on injured reserve after he suffered an ankle injury in December.
A journeyman who has played for five teams across 10 NFL seasons, Ihedigbo may have trouble finding work next season. He was on the open market until the midway point of last season before Buffalo brought him in due to injuries in the secondary, and he lost his starting job in 2015 with the Detroit Lions.
A four-game suspension won't do anything to help a player who was barely hanging on at the NFL level.