Bridget Jones (Renée ZELLWEGER) - a 30-something London girl - wakes up on New Years' Day, hung over and still single. Worse still, she has to attend her parents' annual turkey curry buffet. The buffet is in full swing when Bridget arrives; amongst the guests is the very eligible lawyer Mark Darcy (COLIN FIRTH). At first glance, Bridget is impressed by Mark Darcy but after an awkward exchange, she overhears him being rude about her to his mother. She resigns herself to the fact that she is destined to remain a 'singleton'.
Back in London, Bridget is determined to get a grip on her life. She decides to keep a diary and makes a set of New Year resolutions which include losing weight and finding a 'nice sensible boyfriend'. In particular she is determined to stop fantasising about the handsome and enigmatic Daniel Cleaver (HUGH GRANT), her boss in the publishing company where she works. But back at work Bridget humiliates herself in front of Daniel and calls for 'an emergency summit with urban family" - her three best friends - Tom (JAMES CALLIS), a 'pop icon who only wrote one song', Jude (SHIRLEY HENDERSON), a 'petite business dynamo', and Shazza (SALLY PHILLIPS), a 'journalist who likes to say 'fuck' a lot." As usual, packs of cigarettes are smoked and litres of vodka consumed as the friends discuss Bridget's crush on Daniel.
Over the next few days, Bridget and Daniel exchange flirtatious and sexy e-mails. Then, at the launch party for a new book, Bridget, egged on by the advice of her friends, decides that she will ignore Daniel and "be fabulous with everyone else" to make him jealous. But thrown by the presence of Mark Darcy who is there with Natasha (EMBETH DAVIDTZ), and overawed by the distinguished literary figures, Bridget's façade is soon shattered.
After her attempt at an introductory speech goes horribly wrong, Daniel insists on taking Bridget to dinner. At dinner Daniel tells Bridget that he and Mark had been friends until Mark had an affair with his fiancé. Afterwards, Bridget and Daniel kiss and although she attempts to resist his invitation to return to his place, that's exactly where she ends up. Bridget is triumphant until her Mother (GEMMA JONES) tells her she is leaving Bridget's Dad (JIM BROADBENT) for a presenter at the Home Shopping Channel called Julian, who thinks she has 'potential'.
Meanwhile, Daniel has agreed to take Bridget away for a weekend and will accompany her to a Tarts and Vicars party being held by friends of her parents. When they arrive at the hotel, they discover that Mark and Natasha - also en route to the Tarts and Vicars party - are guests at the same hotel.
That doesn't stop Bridget and Daniel having fun on the lake or in their room, however, but when Sunday morning comes, Daniel disappoints Bridget by telling her he must return to London for a meeting. On the way back, Daniel drops Bridget at the Tarts and Vicars party. Dressed as a bunny-girl, to her horror, Bridget soon sees that no-one else is in fancy dress. Mark and Natasha are there looking immaculate and her Mother has come with her new boyfriend Julian. Only one other guest is in costume - Bridget's father, sitting forlornly on a toadstool in the garden, dressed as a vicar.
Afterwards, Bridget heads straight for Daniel's flat where she discovers Daniel in flagrante with Lara, an American colleague. So that was his 'meeting'. She leaves, hurt and confused. Reluctantly back at work the following day, Bridget learns from Daniel that he and Lara are engaged. She goes home dejected but once again determined to take control - and get a new job!
Soon enough she finds one - with a TV current affairs programme, Sit Up Britain - and leaves the publishing company in a moment of triumph. Her first assignment - covering a London fire station on Bonfire Night - is a disaster. But her appeal is irresistible and her boss, Richard Finch (NEIL PEARSON), is amused.
That evening Bridget runs into Mark - and Natasha - once again when they are guests of her 'smug married' friends, Magda and Jeremy. There, in a nightmare situation, she is surrounded by couples asking questions about her love life. Bridget hits back by reminding the 'smug marrieds' how many marriages end in divorce and her comments are endorsed by Mark. When she leaves, Mark surprises Bridget when he tells her not only that he likes her - but that he likes her "just as you are"...
Her next assignment for Sit-Up Britain is to interview a British aid worker married to a Kurdish Freedom Fighter whom the Government want to extradite. She can scarcely believe her luck when she discovers that the case is being handled by Mark - her interview is assured and a huge success.
It's her birthday and Bridget is cooking dinner for Tom, Jude and Shazza. Her preparations are disastrous but when Mark turns up unexpectedly to congratulate her on the success of the interview, he helps her to sort out the carnage in the kitchen. By the time her friends arrive, Bridget and Mark are very comfortable in each other's presence. The evening is dramatically interrupted by the arrival of Daniel, begging Bridget's forgiveness and declaring his love. Mark is crushed and leaves but, within moments, he is back challenging Daniel to a fight. As Bridget and friends watch in horror, Mark and Daniel fight until one final resounding punch from Mark brings Daniel crashing to the ground.
Bridget rushes to Daniel's side, completely alarmed by Mark's violent behaviour. Daniel tells Bridget "if he can't make it with her, he can't make it with anyone", but that's not enough for her... She resigns herself once more to her 'singleton' status.
Christmas comes round again and Bridget is home with her Dad when her Mother returns recovered from her mid-life crisis. The following day, the Jones' are to attend the Darcys' ruby wedding party when Bridget learns from her Mother that it was in fact Daniel who ran off with Mark's wife and not the other way round
At the Darcys', Mark is cold towards Bridget until she explains that she knows the truth about Daniel and reveals that she has fallen for him. They are interrupted by Mark's father who makes a speech announcing that Mark is going to America. Bridget embarrasses herself by publicly telling Mark not to go and declaring that she loves him. She then leaves in a hurry....
Back home in London, Bridget's friends arrive to take her on a surprise trip to Paris to cheer her up. As they are piling suitcases into the car, Bridget is amazed to see Mark walking towards her. They retreat upstairs together and Bridget decides to slip into some sexy underwear. While she's gone, Mark reads her diary, seeing some of the negative things she's written about him. When she hears the door slam and sees him walking away from the window, she realises what's happened. She charges down the stairs and sprints out into the snow after him. As she searches wildly for him, he emerges from a shop - with a new diary - and....
...... they passionately embrace