The film is to be based on Helen Fielding’s 2013 novel, Bridget Jones: Mad About The Boy, which explores Jones as a 51-year-old single mother to two children in an era of social media and dating apps.
A source told the newspaper: “Bridget is back and is about to take over London. Filming is being mapped out already and all of the pre-production is in place.”
Zellweger, 54, is said to be “excited” about reviving the British icon.
“She adores the character so much,” the source said, adding: “Bridget Jones fever is expected to sweep across London.”
Colin Firth and Hugh Grant, who played love rivals Mark Darcy and Daniel Cleaver in the previous films, are also expected to make a return.
It comes eight years after Bridget Jones’s Baby hit screens, which ended with Zellweger’s character marrying high-flying lawyer Darcy and discovering he was the father to her child.
She previously told Radio Times about the movie: “I think it’s really difficult to make films and to make them happen and to make them good and we want it to be really good. But I really hope so. I’d love to see it on the screen.”
Texan-born Zellweger is said to be looking for somewhere to live in London with her boyfriend, TV presenter and former Hertfordshire Constabulary policeman Ant Anstead while she is working on the project.
She rented an apartment in Kensington, west London, while filming previously, where she would often go unnoticed in the local shops.
Bridget Jones has become a global box office sensation since the first movie, Bridget Jones’s Diary, came out in 2001 and grossed £222 million ($454.8m).
The latest instalment in 2016 also broke UK box office records, bagging £8.11m ($16.6m) in its opening weekend – the largest sum for any September opening and the record for any romantic comedy.