Carrie strolls through the vibrant streets of New York City, reflecting on the lives of her friends and the rollercoaster events that have unfolded during Sex and the City. Charlotte is now blissfully married to Harry Goldenblatt, but her journey to motherhood was fraught with challenges, leading them to adopt a charming Chinese girl named Lily. Meanwhile, Miranda has embraced life in Brooklyn with Steve as they navigate parenthood with their son, Brady. Not one to stay put, Samantha has shifted her business to Los Angeles, close to her superstar boyfriend Smith, yet she finds herself longing for her past life and seizes every chance to return to her friends in the East.
Carrie is caught in the whirlwind of a romance with Big, and they're exploring neighborhoods together, contemplating a move in. One apartment, a stunning penthouse, captures Carrie's heart—even if it’s well beyond their budget. Big eagerly agrees to finance it, leading Carrie to consider selling her own place. However, she voices her concern—it’s not just a home; it's a matter of security if their relationship were to change, given that they're not wed. To alleviate her worries, Big proposes marriage. Carrie joyfully shares this news with her friends. While Charlotte and Miranda enthusiastically cheer her on, Samantha, with her trademark sarcasm, seems more thrilled about the idea of Carrie finally getting Botox. In the midst of wedding plans, Charlotte suggests her flamboyant gay friend, Anthony Marantino, to take the lead as a wedding planner.
As they discuss relationships, Miranda confides that due to her hectic life, she hasn’t been intimate with Steve for six months. The revelation turns into heartbreak when Steve admits to infidelity, sending Miranda into a tailspin as she confronts the reality of their crumbling relationship. During Carrie and Big’s rehearsal dinner, tensions rise as Steve attempts to reconcile with Miranda—only to face rejection. Miranda bluntly conveys to Big her belief that “marriage ruins everything,” a sentiment that hovers over the wedding day.
On the fateful day of the ceremony, plagued by doubts fueled by Miranda’s earlier comments, Big hesitates to follow through. In a moment of despair, Carrie bolts, leaving a trail of shocked guests. Samantha remains to manage the fallout while Big chases after Carrie, resulting in a heated confrontation in the middle of a bustling street where Carrie dramatically lashes out with her bouquet. Feeling bewildered and hurt, she opts for a getaway with her friends to the honeymoon destination she had envisioned, Mexico, where they seek solace and rejuvenation.
Upon their return to New York, Carrie hires an assistant named Louise, who helps her juggle her chaotic lifestyle. As tensions rise, Miranda finally reveals the truth about the rehearsal dinner to Carrie, leading to a friendship tumble on Valentine's Day. Taking time to reflect, Miranda decides to attend counseling with Steve—a choice that ultimately aids in mending their relationship. Meanwhile, Samantha grapples with a passionless five-year relationship, setting her sights on self-prioritization, which leads her to part ways with Smith and return to New York. Shortly thereafter, Louise bids farewell to her assistant role to embark on her own journey toward marriage.
In a surprising twist, Charlotte discovers she is pregnant. Initially filled with anxiety about her baby’s safety, her fears are put to rest when Carrie comforts her with a humorous quip about her “bad luck” running out. A shocking encounter with Big sends Charlotte into labor, leading him to be her unexpected support at the hospital as they await the birth of baby Rose. Messages get relayed, and Carrie, backed by newfound determination, dives into her correspondence and uncovers heartfelt letters Big had written, pouring out his feelings and remorse for the past.
Determined to find closure, Carrie returns to Big's newly-acquired penthouse to reclaim a pair of iconic Manolo Blahnik shoes. There, she unexpectedly finds him in the closet, and upon seeing him, her lingering resentment melts away. They share an electric kiss, and Big proposes earnestly, ingeniously using one of her diamond-encrusted shoes instead of a traditional ring.
The film culminates in a simple yet intimate wedding at New York City Hall where Carrie dresses in the understated attire she originally planned to wear. To her delight, Miranda, Samantha, and Charlotte show up, surprising her with their presence, thanks to Big's prompt. The story concludes with the four friends relishing cosmopolitans while celebrating Samantha's milestone fiftieth birthday, with Carrie raising a glass to toast the adventures of the next fifty years.
