The 19-year-old forward joins David Unsworth’s title-winning Under-23s team from German Bundesliga club Wolfsburg.
But now the German is back to full fitness, he is delighted to be given another opportunity with Everton.
“I’m very happy to be back,” Donkor said. “I’m looking forward to pre-season to show my teammates and the fans that it was the right decision for the Club to re-sign me.
“But I got fit again quickly and now I’m feeling better than before. I’m feeling at 100 per cent.”
Donkor has been training with the Under-23s at Finch Farm during the first week of pre-season.
“Training so far has been very good and tough,” he added. “After six weeks I hadn’t played football, but I was very happy to be back out on the pitch. David Unsworth is a great guy and I enjoy training with him. He has a good style of coaching.
“I love it here and English football is perfect for me. I’m very happy to be back.”