And he has not ruled out a showdown with the British super-middleweight king.
DeGale will feature in an eight rounder on the show, headlined by Ricky Burns' WBO world super-featherweight title defence against Joseph Laryea.
Johnson, the 2010 Commonwealth Games champion, is also on the undercard and says the Olympic champion's presence will give everyone fighting a boost.
The 25-year-old from Lincolnshire will feature in a four-rounder against Scunthorpe's Jody Meikle (0-3).
"He's one of the hottest talents in boxing right now, and there will be a real buzz on Saturday night," said Johnson.
"I watched the way he dealt with Paul Smith and he really impressed that night.
"It's rare for someone who has had so few professional fights to put in such a polished performance.
"I think James will definitely sprinkle some star-dust around on Saturday, and the crowd will be in for a treat."
Johnson knows how good DeGale is only too well - he lost to him as an amateur in the ABAs a few years ago.
But Johnson has been dreaming of a return ever since.
"James is obviously a quality boxer, as I found out myself," he said.
"But I'd like to think that given my development over the next couple of years, I could one day get my own back.
"I'm fighting at light-heavyweight at the moment and he's at super-middle, so there's a pretty good chance that we will meet one day somewhere down the line.
"Given that he's won an Olympic gold, I'm a Commonwealth champion and we're both British, it's a big domestic showdown and I'm sure that it would be fight that would sell pretty well."
Johnson, 25, made his professional debut in December, recording his first victory with a second-round stoppage of Phillip Townley.