The Bills outscored the Steelers 16-3 in the second half to force the overtime, but let the victory slip through their fingers, literally, as Johnson dropped a wide-open pass in the end zone.
Buffalo quarterback Ryan Fitzpatrick could only watch as Johnson dropped the sure touchdown and Pittsburgh drove 80 yards on the game's next series to set up the game-winning 41-yard field goal by Shaun Suisham.
Johnson was reluctant to accept responsibility for the gaffe, posting on his Twitter account post-game that it was in fact God's fault.
"I PRAISE YOU 24/7!!!!!! AND THIS HOW YOU DO ME!!!!! YOU EXPECT ME TO LEARN FROM THIS??? HOW???!!! ILL NEVER FORGET THIS!! EVER!!! THX THO...," Johnson tweeted.
Fitzpatrick finished the day completing 23 of 45 passes for 265 yards in the loss.
Suisham, who was brought in earlier this month after the Steelers waived long-time kicker Jeff Reed, provided the bulk of Pittsburgh’s points, converting four of four field goals at Ralph Wilson Stadium.
Steelers running back Rashard Mendenall ran for 151 yards and one touchdown on 36 attempts to help keep Pittsburgh in position to win the tight game on the road.
Quarterback Ben Roethlisberger threw for 246 yards, completing 20 of 33 passes.
The result snapped Buffalo's two-game winning streak after a miserable 0-8 start to the season.
The team now travels to Minnesota to take on the Vikings, who are 4-7 coming off a win over the Washington Redskins.
Pittsburgh, 8-3, heads to Baltimore next Sunday night to square off against AFC North rivals the Ravens.