It was not immediately clear why he was suspended.
The Cardinals released Nkemdiche, their 2016 first-round pick, in July, one day after he arrived at training camp out of shape.
The Dolphins signed him to a one-year deal worth up to $1.1 million in August. He was placed on the physically unable to perform list as he continued to recover from a torn ACL suffered in December 2018 and get into better playing shape.
He was released last week after playing just two games with the Dolphins.