The skilful forward enjoyed a blistering start to Oakwell life by netting his first ever senior goal just minutes into his debut in front of an electric crowd of 11,400 in the Johnstone's Paint Trophy.
Reds Head Coach Lee Johnson spoke of his delight at keeping the striker to the end of the current campaign.
"I'm really pleased and very grateful to Manchester United for allowing us to keep Ashley to the end of the season.
"He has been a real asset to the group since joining and has improved with each game. He'll only get better and stronger as we go along, so we're all extremely excited to have him on board as we head towards the business end of the season."
The 20-year-old has so far made four appearances for Lee Johnson's side, starting his first game on Tuesday night in our 1-0 win at Bradford City.
Ashley himself added, "I'm delighted to be staying here as I've really enjoyed my time here so far. The dressing room is a great place to be and I'm excited looking ahead at the games coming up. I feel I will only get better as I get more experience under my belt and I want to help the team as far up the league as possible, so who knows where we can go."
