Both fighters came under the 168-pound limit ahead of their showdown at the O2 Arena in London.
James DeGale weighed in at 166lbs, while Chris Eubank Jr tipped the scales at 167.5lbs.
DeGale has labelled the clash the “retirement fight”, saying the loser won’t have anywhere to go after tonight’s encounter is settled.
The 33-year-old said: ”When he first turned professional he was calling me out – he’s very deluded.
JAMES DEGALE VS CHRIS EUBANK LIVE: FOLLOW THE FIGHT FROM THE O2 ARENA
“[Tonight] I get my chance to deal with this guy good and proper and finish him.
“After Eubank has lost to me I don’t know where he is going to go.
“I’m calling this the retirement fight and whoever loses can knock it on the head, it’s game over.
“He’s got heart and big set of balls but that’s not going to be enough to beat me.”
In contract to DeGale, Eubank Jr insists retirement is not something he has considered.
He said: “James talks retirement, but that has never even come into my mind.
“I hope he can bring the best he can bring on the night and give the fans the most exciting and explosive fight that we possibly can.
“I just don’t think he has what it takes.”
DeGale vs Eubank Jr LIVE stream – how to watch
ITV Box Office will be broadcasting live TV coverage of the fight in the UK.
Live streaming of the action is available through TVPlayer, which can be accessed on across a range of devices.
The undercard is due to get started at 7pm, which main event expected to take place around 10pm.
DeGale vs Eubank Jr is a per-per-view event and will cost fans £19.95 to book.