The film begins with Jane (Katherine Heigl) providing a voiceover that takes us back to her childhood, where she first realizes her true calling in life. This poignant flashback occurs at a family wedding shortly after the death of their mother, with Jane stepping into the role of a mother figure for her younger sister, Tess, while their father is preoccupied. When Jane is tasked with taking Tess to the bathroom, she encounters an upset bride who has suffered a wardrobe malfunction. Seizing the moment, Jane ingeniously uses her sister's hair ribbon to sew the dress, earning the bride's gratitude as she asks Jane to carry her train down the aisle.
As the story shifts to the present day, we find Jane amidst the bustle of a bridal shop, expertly hemming a wedding gown for a bride who is in a panic just hours before her ceremony. Dressed in her own bridesmaid attire, Jane dashes to the wedding venue, arriving just in time for the bride to change. During the ceremony, Jane's anxious glances at her watch catch the attention of a wedding guest, Kevin (James Marsden), who notices her impatience. When a lull occurs in the festivities, Jane bolts outside and offers a taxi driver $300 to keep his eyes off her during the ride, which sparks a series of wardrobe changes as she is enlisted as a bridesmaid for multiple weddings on the same night.
The evening reaches a crescendo when the bouquet toss at the first wedding turns chaotic, leading to Jane being knocked unconscious by overzealous guests. Upon regaining consciousness, she finds Kevin at her side, and a charming connection begins to form between them as they share a ride home. Their conversation ignites a debate about the sanctity of marriage, with Jane feeling annoyed yet intrigued by Kevin's views.
As Kevin discovers Jane's extensive history of attending weddings through her day planner, he pitches the idea of writing a feature on her for the local newspaper. Meanwhile, at work, Jane's feelings for her boss, George (played by Edward Burns), are painfully evident as she watches her sister Tess charm him, leading to a burgeoning romance. Tensions rise as Jane continues sacrificing for Tess's happiness, all while carrying her own secret longings.
With each passing moment, Jane navigates the complexities of her life, confronting the uncomfortable truths of her suppressed feelings for George and the escalating rivalry with Tess. The emotional roller coaster intensifies as Jane grapples with her identity, aspirations, and the unfolding chaos surrounding her family's wedding plans.
When Jane attempts to assert herself, public revelations, personal conflicts, and chaotic events culminate in an impactful climax that tests her relationships and pushes her toward a necessary self-realization. Following unexpected encounters and heartfelt apologies, Jane ultimately embraces the possibility of love with Kevin.
The film concludes with a heartfelt wedding of its own, where Jane finally finds her place among her bridesmaids, each draped in the colorful dresses that symbolize her journey through love and friendship. Amidst the picturesque backdrop of her beach wedding, Jane discovers that true love is not just a fairytale, but a beautiful reality she can finally call her own.
