Johnson joined the Bills in 2014 after spending the previous 13 seasons with the New England Patriots. He is under contract with Buffalo through 2016, so he would need permission from the team to leave.
The 50-year-old Johnson has a history with the Giants, having played for them from 1986-92 and winning two Super Bowls with the team. He told the New York Post on Wednesday he would welcome an opportunity to return to his former team as a coach.
"I would have to calm down my emotions, but I would love that opportunity," he said.