The 2008 Olympic gold medallist has taken the professional ranks by storm and closed out a superb 2010 by wading into deep waters to dethrone domestic super-middleweight champion Paul Smith.
The Londoner took a calculated risk by challenging Smith in the holder's native Liverpool despite never previously gone beyond five rounds.
However, he produced a performance of style, substance and maturity from the first bell to ease his way to a ninth-round stoppage and comfortably ascend to title level.
DeGale said: "I'd like to win the Lonsdale (British title) belt outright but we'll just have to see. This time next year I want to be European champion. Easily, by this time next year. By 2012 I'm going to be a world champion or knocking on the door for a world title."
DeGale, who displayed power and grit as well has his trademark skill and speed, was in control throughout at the Echo Arena with Smith limited to lunging forward and enjoying only sporadic success. In the ninth, the 24-year-old stepped it up and was landing damaging shots with both hands and having already hurt Smith in the round, a second sustained attack prompted referee Howard Foster to wave it off and give DeGale the belt.
Also on the bill, Nathan Cleverly won a unanimous points decision to claim the vacant WBO 'interim' light-heavyweight world title against France's Nadjib Mohammedi, Matthew Macklin retained his European middleweight title and Kell Brook claimed his 23rd win.