It's the beginning of the new year for Bridget Jones (RENÉE ZELLWEGER), a 32-year-old, single woman who works at London publishing house. Determined to improve her life by losing weight, cutting down on cigarettes and booze, and finding a man, Bridget begins keeping a diary to record her attempts and thoughts about such efforts.
While the first two are up to just her, the latter obviously requires a willing man. Among her immediate choices is Mark Darcy (COLIN FIRTH), a staid and proper, but divorced barrister who she's known but not particularly liked since they were kids. Then there's Daniel Cleaver (HUGH GRANT), a terribly charming and handsome chap who just so happens to be her boss.
After a bout of flirting, she chooses Daniel - who claims Darcy stole his fiancée in the past - and they begin a passionate affair. Yet, when one part of her life goes well, the other inevitably falls apart as she discovers that her parents (JIM BROADBENT and GEMMA JONES) are separating, with her mother beginning a relationship with her boss, a TV shopping channel host.
Bridget's close friends, Tom (JAMES CALLIS), Shazza (SALLY PHILLIPS) and Jude (SHIRLEY HENDERSON) couldn't be happier for her regarding her relationship, while Darcy - who's involved with fellow lawyer Natasha (EMBETH DAVIDTZ) - seems a bit disturbed by that and even somewhat interested in Bridget.
Bridget's happiness ends, however, when she discovers Daniel with another woman. From that point on, and with the help of her friends, Bridget decides to follow through on her resolutions that ultimately include choosing between Daniel and Darcy as her lover.