PSG suffered their first loss of the season in Ligue 1 - a shock 3-2 defeat at home to Nice on Friday night.
Moffi was on the scoresheet twice, netting the opener in the 21st minute before making it 3-1 with 20 minutes to go after Mbappe and Gaetan Laborde had struck.
And his second of the night at the Parc des Princes sparked wild celebrations, ripping his shirt off and roaring into the sky.
The Nigerian showed off his shirt with his name on the back toward the Parc des Princes crowd.
It was a special moment for Moffi, who was playing his second debut for Nice after his loan from Lorient was made permanent this summer.
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But it appeared to irk Mbappe, who was furious with the striker when he returned from his goal celebration.
He had to be restrained by a couple of players as he tried to make his way to the Nice striker, barking at him the whole way.
Moffi looked somewhat stunned but stayed restrained as Mbappe continued his complaints.
Even as the referee intervened, the PSG superstar continued to sulk and snarl as he prowled around the pitch.
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Mbappe would go on to grab a second but even his double could not save PSG as they suffered their first loss of the domestic campaign.
It saw Nice jump ahead of them in the table with the Ligue 1 champions falling to third in the table.
There have been seismic changes at the Parc des Princes this summer where Neymar and Lionel Messi both departed.
Mbappe was also close to leaving after telling the club he did not want to sign a new contract.
It saw PSG chiefs force him to train apart from the main squad as they looked to offload him and even told him he would not play this season.
But that decision was reversed when it became clear that no suitor would pay the £170million price-tag slapped on the France international.
The 24-year-old has entered the final year of his contract at PSG amid interest from Real Madrid and even clubs in the Premier League.