William "Will" Thacker (Hugh Grant) owns an independent travel bookshop in Notting Hill. He is divorced and shares his house with an uninhibited Welsh eccentric named Spike (Rhys Ifans).
Thacker encounters Hollywood star Anna Scott (Julia Roberts) when she enters his shop to buy a book. Minutes later, the pair collide in the street and his orange juice spills on her clothes. He offers his house nearby for Anna to change. Afterwards she surprises Will with a kiss.
Days later, Spike remembers that "some American girl called Anna" had phoned and mentioned a "completely different name". Anna is at the Ritz, under the name "Flintstone". Will is allowed in, but her press interviews are running and he is mistaken for a journalist. (In panic he claims he works for Horse & Hound.) He has to interview the cast of Anna's new film Helix, which he has not seen. Anna calls him back in and says she has cancelled her evening appointment to go out with him. Will is delighted, but his sister Honey (Emma Chambers) is about to have a birthday party, so Anna says she will go as his date.
There, at Max's (Tim McInnerny) and Bella's (Gina McKee) house, Anna feels at home with Will's friends. Afterwards they climb into a private London square. The next day they go to a cinema and a restaurant. Anna invites Will to her room at the Ritz, but her American boyfriend, a famous film star named Jeff King (Alec Baldwin in an uncredited cameo), has arrived unexpectedly. Will pretends to be a room-service waiter. Anna is very embarrassed and disappointed, and apologises when King steps out of the room; she thought he had broken up with her. Will realises he must leave. He then tries to forget Anna, but finds it very difficult.
Six months later, Anna turns up at Will's house, unannounced. Old pictures taken of her as a cheesecake model have been sold to the press and she needs a place to hide out. After spending the day together, Anna goes downstairs to where Will is sleeping and they embrace. They go up to the bedroom and make love, and in the morning Anna asks if she can stay longer. "Stay forever", says Will. The doorbell rings and they are stunned to see a horde of reporters, alerted by Spike's careless talk at the pub. Angry at what she views as Will's betrayal, Anna leaves and he again attempts to forget her.