He gave the Steelers a 10-0 lead with a little more than two minutes left in the first quarter.
It was the Steelers' first punt return for a touchdown since Antonio Brown scored one against the Colts in 2015.
Johnson fielded the ball deep on the Steelers' sideline before crossing the field to streak up the opposite sideline, with help from his teammates' blocking, for the score.
It's Johnson's first NFL punt return for a touchdown, but he scored one in his final season at Toledo a year ago.
Johnson took over return duties full-time when Ryan Switzer went on injured reserve prior to the Nov. 14 game against the Browns. Before the 85-yard return, Johnson was averaging 7.1 yards per return. His longest was 14 yards.