Johnson was due to make $3.2 million in base salary this year. He caught just 18 passes last season.
Lions general manager Martin Mayhew informed Johnson's agent of the decision in a morning phone call.
"He didn't really have much to say about it," Johnson's agent, Chafie Fields, said. "We knew it was a possibility, so it wasn't a total, complete blindside. It's not a situation where he took it personal."
The Lions also closed in on a deal to re-sign cornerback Brandon McDonald, two people familiar with the deal said.