Both books were adapted as hit films starring Renee Zellweger as the titular heroine and Colin Firth and Hugh Grant as her handsome suitors -- the respectable, but restrained Mark Darcy and devilish Daniel Cleaver.
The New York Times said Fielding's as-yet-untitled book will be set in present day London and "represents a totally new phase in Bridget's life."
"Bridget Jones's Baby," a film based on the last of Fielding's newspaper columns, is in the works with Zellweger, Firth and Grant to reprise their roles.
It is unclear whether the new book will pick up where the last film or book or newspaper column left off, or it is an entirely new story.
A "Bridget Jones" stage musical is being developed.