Disetkan empat tahun selepas peristiwa-peristiwa penghabisan siri, filem bermula dengan suatu montaj Carrie (Sarah Jessica Parker), Samantha (Kim Cattrall), Charlotte (Kristin Davis) dan Miranda (Cynthia Nixon) berjalan melalui New York dan suatu recap dari adapa yang telah berlaku dalam siri TV dan juga apa yang telah berlaku di antara penghabisan musim enam dan filem. Ia kemudian berloncat ke Carrie dan Big (Chris Noth) melihat pangsapuri dengan niat berpindah masuk sama. Carrie minat dengan sebuah suite penthouse jauh dari julat harga mereka, yang Big selanjutnya bersetuju untuk membayarnya. Meskipun, Carrie mengalami doubts ke atas kebijaksaan aturan ini, menjelaskan bahawa mereak tidak berkahwin, dan oleh itu dia tidak akan mempunyai hak legal pada rumah mereak dalam peristiwa pemisahan. Dia menawar untuk menjual pangsapurinya, dan menghilangkan rasa takutnya, Big bercadang mereka berkahwin.

Miranda (Cynthia Nixon) sedang mencari seimbangan rumah, kerja dan hidup sosial adalah lebih sukar, dan mengaku pada kawan-kawan perempuannya dia tidak mengadakan hubungan seks dengan Steve (David Eigenberg) selama enam bulan. Dia devastated apabila Steve mendedahkan dia telah meniduri dengan perempuan lain, dan selanjutnya Miranda berpisah dari Steve. Samantha (Kim Cattrall) sedang tinggal dengan Smith (Jason Lewis), yang mempunyai suatu pekerjaan televisyen yang berjaya memainkan seorang doktor di sebuah lipur lara masa perdana. Mereka tinggal di sebuah pangsapuri kemewahan di Malibu (berhampiran dengan Los Angeles), di mana Samantha mendapatinya sukar untuk menggunakan waktu untuk dirinya. Dia sedang mengembara sering di antara L.A. dan New York, dan bergelut dengan nafsu berahi tidak henti-henti dengan lelaki lain; jiran sebelah yang tampan dan aktif secara seksual, Dante (Gilles Marini), pada khususnya. Charlotte (Kristin Davis) bergembira dalam perkahwinannya dengan Harry (Evan Handler), dengan anak perempuan angkat mereka, Lily (Alexandra dan Parker Fong).

Carrie diberikan gaun perkahwinan Vivienne Westwood selepas memodelnya untuk suatu gambaran foto dalam Vogue. Carrie membaca kepada Big dari sebuah buku sura tcinta masyhur dia telah pinjam dari New York Public Library. Dia mengusik Big oleh kerana tidak pernah mengirimnya sepucuk surat cinta. Sementara mengembalikan Love Letters of Great Men, Vol. 1 ke perpustakaan, Carrie melihatkan suatu perkahwinan dipegang di sana dan memilihnya untuk tempat sendirinya. Rancangan perkahwinan Carrie bertambah ke sebarang peristiwa mencurahkan, yang Big bermula untuk mengalami keraguan.

Selepas suatu perdebatan dengan Steve di makan malam latihan, Miranda, masih sakit hati tentang percakapan yang tidak bijaksana Steve, memberitahu Big secara berterus-terang bahawa dia dan Carrie adalah gila memikirkan kahwin, oleh kerana perkahwinan akan merosakkan semuanya. Pada hari majlis, Big tidak dapat melalui perkahwinan, tetapi cuba berulang kali menelefon Carrie tetapi gagal. Seorang Carrie yang dibinasakan melarikan diri dari perkahwinan. Big berubah fikiran dan memintas dengan carrie apabila dia melihat limosin Carrie memandu jauh. Carrie, humiliated and betrayed, furiously attacks Big with her bouquet while he earns scathing looks from Miranda and Charlotte. The four women subsequently take the honeymoon that Carrie had booked to Mexico, where they de-stress and collect themselves.

Upon her return to New York, Carrie hires an assistant, Louise (Jennifer Hudson), to help her move back into her old apartment and manage her administration. Charlotte learns she is pregnant after a visit to her doctor. Miranda eventually confesses to Carrie about what happened during the night of the rehearsal dinner, and the two have a brief falling out. After reflecting on the argument she had with Carrie, Miranda agrees to attend couples counseling with Steve, and they are eventually able to reconcile. Samantha begins over-eating to keep from cheating on Smith with Dante, but eventually realizes that their relationship is simply not working, and that she needs to put herself first. The two break up, and she moves back to New York. Charlotte for several months is concerned that something might happen to the baby, because she feels her life seems to be too perfect.

A surprise encounter with Big at a restaurant leaves Charlotte so outraged that she goes into labor. Big drives her to the hospital, and waits until baby Rose is born, hoping to see Carrie. Harry passes on the message that Big would like her to call him, and that he has written to her frequently, but never received a reply. Carrie searches her correspondence, before realizing that Louise has kept his e-mails password-protected from her, after Carrie earlier announced she wished to sever all communication with him. She finds that he has sent her dozens of letters copied from the book she showed him in the weeks before their wedding, Love Letters of Great Men, Vol. 1, culminating with one of his own where he apologizes for screwing it up and promises to love her forever.

One hour before the locks are due to be changed on their shared penthouse apartment, Carrie travels to the home Big had bought for them to collect a pair of blue Manolo Blahnik shoes she had left there. She finds Big in the walk-in closet he had built for her, and the moment she sees him, her anger at his betrayal dissipates. She runs into his arms and they share a passionate kiss. After spending the final hour in their apartment together making up, talking and apologizing to one another, Big proposes to Carrie properly, using one of her diamond-encrusted shoes in place of a ring. They later marry alone, in a simple wedding in New York City Hall, with Carrie dressed in the original dress she had bought in a vintage shop and the blue Manolos. After Big kisses the bride, he whispers into her ear "Ever thine. Ever mine. Ever ours.", a line by Ludwig van Beethoven Carrie read to him from Love Letters of Great Men, Vol. 1 earlier in the film. They hold a get-together at a local diner with their friends. The film ends with the four women around a table in a restaurant, sipping cosmopolitans, and celebrating Samantha's fiftieth birthday, with Carrie making a toast to the next fifty.