The Italian outfit beat Craiova 2-0 in the second leg of their Europa League third qualifying round clash in front of 65,673 fans at the San Siro as they cruised into the play-off round after winning 3-0 on aggregate.
Donnarumma, who made his debut for Milan as a 16-year-old, was heavily linked with a move away over the summer as he stunned supporters in June when his agent Mino Raiola told the club he would not sign a new deal.
However, after months of negotiations, the 18-year-old finally agreed terms for a new five-year contract at worth £5million-a-season.
And following the European clash on Thursday, Donnarumma, who was the target of heaps of fake money thrown by his own fans during Italy Under 21s’ clash with Denmark at the European Championships in June, was delighted with the reception he was given by Milan supporters.
‘I thank the supporters for the welcome and cheers they gave to me,’ Donnarumma told Milan TV.
‘I didn’t expect it, but I am happy at the way they greeted me and promise I will always give everything for this jersey. They know I am Milan’s first fan.
‘For me it is as if nothing happened. I have always been myself and I try to help my team-mates the way they help me.
‘We are working well and the credit for the two clean sheets over two legs is down to the whole team. I thank my team-mates.’