The young Dons have been the best in their league this season and held an 11-point lead over Celtic, who could only draw 0-0 with Falkirk on Thursday afternoon.
The Glasgow side needed to win to have any chance of halting Aberdeen and the latter can now celebrate their triumph.
Coach Paul Sheerin only took charge of the under-20s at the start of the season, but has done a superb job ensuring continuity from the AFC Youth Academy.
Sheerin said: "The lads have worked very hard all season and I'm delighted they have achieved this.
"We haven't won the youth league for a while, so it is a credit to how they have pulled together and played for one another throughout the season.
"I'd like to think the future of the club is in good hands and there are plenty of talented boys in the squad.
"Hopefully, in two or three years' time, they can be making their mark [with the senior side]."
The next match against Dunfermline will take place on Tuesday, May 5 at Pittodrie with a 7pm kick-off.
And entry is free as the club strive to attract a good crowd to salute the team's heroics.
Sheerin added: "It would be nice if we could have a decent support come along to wish these lads well, because they have done Aberdeen proud."
BREAKING NEWS: Aberdeen Football Club U20's- SPFL Development League Champions 2014-15 pic.twitter.com/p6TrVtluu3
— Aberdeen FC (@AberdeenFC) April 30, 2015
Source: STV