As a devoted, albeit challenged, father of three, Daniel Hillard, a freelance voice actor, finds himself at odds with his work-driven wife Miranda, an interior designer who sees him as immature and unreliable. The tension escalates following a heated argument about a script, leading Daniel to quit his job and throw a chaotic birthday celebration for their son Chris—which Miranda vehemently protests due to Chris's struggling academic performance. This conflict culminates in Miranda's abrupt declaration that she wants a divorce, leaving Daniel feeling lost and uncertain about how to support his family moving forward.
After Miranda is granted sole custody, with Daniel allowed visitation only on Saturdays if he can secure stable employment and housing within three months, he realizes he must quickly get his life together. He manages to find an apartment and lands a job as a shipping clerk at a local TV station, but his personal challenges only continue to multiply. When Daniel learns that Miranda is looking for a housekeeper, he seizes the chance to regain some influence over his family's lives.
Harnessing his exceptional voice skills, he secretly alters Miranda’s classified ad and takes on various unpleasant personas before finally presenting himself as Euphegenia Doubtfire, a sophisticated elderly British nanny with top-notch credentials. Miranda, impressed by Mrs. Doubtfire's qualifications, unwittingly invites her for an interview, oblivious to the fact that she is engaging with Daniel in disguise.
With the invaluable assistance of his brother Frank, a talented makeup artist, and Frank's partner Jack, Daniel skillfully transforms himself into an authentic elderly woman through makeup and prosthetics. As Mrs. Doubtfire, he charms Miranda during the interview, successfully landing the job as their new housekeeper.
As the children navigate life under Mrs. Doubtfire's guidance, they initially find her strict yet gradually come to appreciate her unique wisdom and nurturing care. Meanwhile, Miranda becomes more relaxed and begins to rebuild her relationship with her kids, while Daniel seizes the opportunity to acquire essential household skills and earn his wife's respect.
However, as time progresses, Miranda grows increasingly reliant on Mrs. Doubtfire’s capable care, remaining oblivious to the true identity of the kindly old woman. Complications arise when she begins dating an old acquaintance, Stu, which causes Daniel distress. Tensions escalate further when Chris catches Mrs. Doubtfire in a precarious situation, causing him to urgently summon the authorities. In a panic, Daniel must reveal the truth, and his children, eager to maintain their father's presence in their lives, agree to keep his secret.
As circumstances intensify, Daniel faces the repercussions of his deception, wrestling with the challenge of reconciling his dual existence as Mr. Hillard and Mrs. Doubtfire. In an unexpected turn of fate, Jonathan Lundy, the CEO of the TV station, discovers Daniel indulging his creative talents on a set for an abandoned children's program. Captivated by Daniel’s extraordinary voice work, wit, and imagination, Lundy invites him to dinner to discuss a potential new show. Coincidentally, this meal coincides with Miranda's birthday celebration at the same restaurant, where Mrs. Doubtfire is also present. Determined to juggle both events, Daniel frantically switches in and out of the iconic Mrs. Doubtfire costume.
As the evening unfolds, Daniel becomes increasingly intoxicated and carelessly reappears before Lundy in full Mrs. Doubtfire attire. With impressive composure, he manages to convince Lundy that Mrs. Doubtfire is a brilliant concept for the new show’s host. Later, during dinner, while enjoying Stu's jambalaya, he discovers that Stu has an allergy to pepper and foolishly decides to add some extra seasoning. Chaos erupts when Stu starts choking, prompting Daniel to leap into action with the Heimlich maneuver, made all the more frantic because his prosthetic mask slips off, revealing his true identity.
In the wake of this revelation, Miranda takes the children and departs, leaving Daniel devastated by the fallout of his choices. At a subsequent custody hearing, Daniel delivers a heartfelt plea, arguing that his unconventional actions stemmed from a deep love for his children and a desire to be involved in their lives. However, the judge remains skeptical, interpreting Daniel's claims as merely another clever ruse, and ultimately grants Miranda full custody while imposing strict limits on Daniel’s visitation rights.
This heart-wrenching decision shakes the family to its core, forcing even Miranda to confront the realization that her animosity towards Daniel had perpetuated a damaging cycle. Deprived of the cherished presence of Mrs. Doubtfire, the entire family descends into sadness, recognizing the profound impact this character had on their lives. They soon discover that Euphegenia's House, the new children's show hosted by none other than Mrs. Doubtfire, has blossomed into a national sensation.
When Miranda visits Daniel on set, she admits that life felt richer when he was more involved as Mrs. Doubtfire. With newfound understanding and empathy, she agrees to negotiate shared custody, granting Daniel the opportunity to spend quality time with his children after school each day. As they leave together, Miranda watches an episode of Euphegenia's House, where Mrs. Doubtfire provides sage advice to a young girl coping with her parents' separation—a heartfelt reminder that amidst life’s challenges, love and unity can ultimately triumph.
