The 34-year-old Johansson is in his rookie season in the NHL. He played in 18 games for the Blackhawks, recording four assists but no goals.
"Magnus is a mobile defenseman that knows how to move the puck quickly and join in on the offensive attack," Panthers coach Jacques Martin said. "He will also provide support on our power play."
Johansson played in the Swedish Elite League from 2004-07 for his hometown Linkoping squad.