The defender was in the right place at the right time to tap in the rebound after a Wojciech Szczesny save, turning the game around following the Alvaro Morata opener and Matteo Politano equaliser.
Koulibaly ‘borrowed’ a camera from a pitch-side photographer and turned it towards the crowd during his celebrations.
“I saw the fans up there and wanted to keep the moment in a photograph, it was too beautiful!” he told DAZN.
“This victory is for them, because we missed them for over a year and to see them back in the stands makes us so happy.”
Morata had given Juventus the lead against the run of play, catching Kostas Manolas in possession.
“We knew that both teams were missing important players, and it’s a pity we conceded that goal, but we had the right maturity to react and change things,” added the Senegal international.
This result means Napoli have had a perfect start to the Serie A season and are already eight points clear of Juve.
“It’s too early, we are not thinking about anything except our own progress, winning one game at a time.”