The soap legend was linked to the Channel 5 series earlier this week, alongside Girls Aloud star Nadine Coyle and comedian Julian Clary.
The actress, who played Bet Lynch in Coronation Street, has now finalised a £300,000 deal to enter the Celebrity Big Brother house this summer, The Sun reports.
Bosses are apparently hoping the 70-year-old will provide similar entertainment to Denise Welch, who won the show in January.
"Julie may be getting on a bit but she's certainly game for a laugh," a source told the paper. "Denise proved that the Corrie stars bring in a decent audience and don't mind poking fun at themselves and having a laugh.
"Julie is keen as mustard to get in the house and is already talking about winning."
Meanwhile, Clary has allegedly secured £325,000 for his stint on the show, with producers hoping he displays his controversial humour.
"He is not afraid to speak his mind and it's usually in a comical way. Big Brother is an adult show so he won't get any flak for coming out with outrageous comments. That's why he will be getting so much cash," the insider remarked.
Former EastEnders actress Cheryl Fergison has apparently agreed a £175,000 fee, while 'beautiful' journalist Samantha Brick has been offered £50,000.
This year's second series of Celebrity Big Brother, as ordered by Channel 5, will air in late summer after the regular series.