The European super middleweight champion parted ways with previous promoter Frank Warren and will begin the latest chapter of his career with a title defence at the Glow exhibition centre in Bluewater.
"I am over the moon with my new long-term promotional deal with Hennessy Sports," said DeGale, whose record reads 12-1.
"I can't wait to get back in the ring on October 13th and show millions of viewers what I’m all about.
"The new beginning is a thrilling prospect, so watch this space."
The 26-year-old Beijing gold medallist at middleweight won the European strap from Piotr Wilczewski in 2011 after losing a majority decision to fierce rival George Groves months prior.
He retained the belt in Denmark, stopping Italian Cristian Sanavia in April, and the Bluewater fight against an opponent yet to be confirmed will be his second defence.
DeGale’s new promoter Mick Hennessy said, "I'm very excited to have signed a brilliant young talent like James Degale.
"To travel to China to fight on away turf and be the only Brit to capture an Olympic gold medal in such difficult circumstances was an amazing feat.
"To already be European Champion after only 13 fights is also an amazing achievement, our goal is to nurture and enhance James extreme talent to the highest level and for him to become not only a genuine world champion but also a cross-over star worldwide.
"I'm very excited to be bringing professional boxing to the Glow for the first time, it is a fantastic arena, perfect for sporting events like boxing."