The Londoner, nicknamed ‘Chunky,’ dropped Dirrell hard twice in the second round and looked on the verge of winning early, but was guilty of taking his foot off the gas in the second half of the fight.
Into the last two rounds, I had the fight on a knife-edge following a great comeback by Dirrell, although DeGale put in a titanic effort in the final two rounds to seal victory.
On the cards after 12, the three judges had it 117-109 and 114-112 (twice) as DeGale secured his lifelong dream of holding a coveted world title belt.
In the co-feature, Edwin Rodriguez ended Craig Baker’s perfect record in the third round, whilst Danny O’Connor and Jonathan Guzman both halted their respective rivals in the fifth.
Also on the bill, Ireland’s Gary ‘Spike’ O’Sullivan impressed with a second round KO win over once-beaten Melvin Betancourt. The 30 year-old kept up his 100 percent record fighting by making it five from five to improve his record to 21-1.
Talented super featherweight Ryan Kielczewski wasted no time defeating Anthony Napunyi as the 25 year-old from Quincy finished off his opponent with just a few seconds left of round one.
Logan McGuinness survived a scare in the first round himself having been dropped by Gerardo Cuevas before going on to win 57-56 on all three cards after six rounds.
Earlier, super middleweight Edwin Espinal beat Alvaro Enriquez on points, whilst Immanuwel Aleem, Antonio Russell and Danny Kelly stopped their foes in the opening session.