The film opens with The Narrator (Helen Mirren) providing an insightful commentary on the societal influence of the Barbie doll throughout history. Accompanying her narration is a nostalgic clip of the original 1959 Barbie, majestically standing against a desert backdrop, while young girls, in a fit of rebellion, attempt to dismantle the conventional baby dolls they once adored.
In a world concealed from reality is Barbieland, a vibrant place where Barbies and Kens, along with other dolls like Allan (Michael Cera) and Midge, thrive. Here, the Barbies dominate with a matriarchal governance, holding prestigious positions, while the Kens are left as unappreciated supporters lingering in the shadows of the Barbies' success. Among them, Beach Ken (Ryan Gosling) harbors unreciprocated feelings for Stereotypical Barbie (Margot Robbie), constantly vying for her attention, yet remaining unnoticed.
Everything takes a turn during a lively dance party at Barbie's residence, where she begins to grapple with her existence and identity. The following day, Barbie faces an existential crisis, plagued by unforeseen issues such as blemishes on her otherwise perfect skin and her beautifully arched feet turning flat. The other Barbies recommend she seek advice from Weird Barbie (Kate McKinnon), who unveils the unsettling truth: the human girl playing with her is unhappy. In order to address her crisis, Barbie must venture into the real world, locate her human counterpart, and extend her support.
On her journey to the real world, Barbie discovers (Beach) Ken hidden in her vehicle. He manages to persuade her to take him along, and both set off for Los Angeles, only to find themselves in humorous predicaments, getting arrested multiple times. As Barbie navigates the flawed complexities of the real world, she learns the power of emotion and empathy, shedding tears while complimenting an elderly woman on her beauty. Meanwhile, Ken explores the allure of the patriarchy, feeling a sense of belonging for the very first time as he journeys back to Barbieland, energized by this new discovery.
Upon reaching a local school, Barbie encounters her human girl, Sasha (Ariana Greenblatt), striving to assist her. However, Sasha and her peers criticize Barbie for emblemizing "bimbo culture" and unhealthy aspirations, causing Barbie to flee, crestfallen. In the meantime, the Mattel CEO (Will Ferrell) becomes aware of Barbie's existence and orders her return to Barbieland, dispatching his team to retrieve her.
As Barbie arrives at the Mattel headquarters, she faces the CEO and his male subordinates who attempt to send her back in a giant doll box. Realizing their intentions, she manages to escape amid the chaos, aided by Sasha and her mother Gloria. Gloria's connection to Barbie is profound; as she reveals that she had turned to Barbie during her own midlife crisis, thus passing her worries on to her toy. Unbeknownst to them, the CEO and his associates are still on their trail as they work their way back to Barbieland.
Upon returning, Barbie and her friends discover that Ken has risen to power, leading an uprising against the Barbies and establishing a regime that reduces them to mere companions. The Kens plot to solidify their newfound patriarchy in the Barbieland constitution the very next day. Determined to reclaim their autonomy, Barbie attempts to sway Ken to revert to the original order, but he stubbornly refuses, reveling in his newfound self-worth. Overwhelmed by despair, Barbie finds a spark of inspiration from Gloria's powerful speech regarding womanhood, igniting her resolve to rescue Barbieland.
In a climactic turn of events, Barbie, Gloria, Sasha, Weird Barbie, Allan, and several other marginalized dolls scheme a rebellion. Utilizing Gloria's passionate address, they liberate the Barbies from their oppression before cleverly inciting discord among the Kens to disrupt their plans for constitutional change. As the Kens engage in a comical showdown on the beach, the Barbies successfully restore the matriarchal system back into their constitution.
In a poignant moment, a heartbroken Ken laments his role as merely an accessory to Barbie. She gently encourages him to embrace his individuality, leading to a heartfelt exchange of apologies between them. The newly appointed President Barbie ([Issa Rae]) then strikes a deal with the Mattel CEO, agreeing to a framework of equality that encompasses the Kens and other sidelined toys.
Still on a journey of self-discovery, Barbie seeks the wisdom of the spirit of Ruth Handler (Rhea Perlman), the co-founder of Mattel and her creator. Ruth assures Barbie that she is not confined to a single definition; rather, her evolution transcends her origins. Invoking visions of motherhood, Ruth encourages Barbie to forge her unique path.
Ultimately, Barbie chooses to embrace life in the real world, adopting the name Barbara Handler. With warmth and excitement, Gloria and Sasha accompany her to a pivotal appointment, where Barbie proudly declares that she is there to see her gynecologist.
