Mr. Bean (Rowan Atkinson) is a well meaning, but hopelessly clumsy and destructive security guard at the National Gallery in London. When the board of directors for the gallery, who despise him for sleeping on the job, fail to fire him due to the chairman (Sir John Mills) threatening repercussions, they immediately decide on a different course of action and have him represent them during the transfer of the portrait Whistler’s Mother to the Grierson Art Gallery in Los Angeles, following its purchase by philanthropist General Newton (Burt Reynolds) for $50 million. The curator of the Grierson, David Langley (Peter MacNicol), impressed with the false profile of “Dr. Bean”, agrees to accommodate him at his house for two months, much to the chargrin of his wife Alison (Pamela Reed). After Bean causes some initial mishaps with the airport police and breaking a family heirloom, Alison leaves for her mother’s house with son Kevin (Andrew Lawrence) and daughter Jennifer (Tricia Vessey).
David soon begins to question Bean’s intelligence after he suggests they head to a theme park and causes mayhem with a ride, and later mess up a dinner with the gallery’s owner, George Grierson (Harris Yulin). His worst fears are soon realised when Bean accidentally ruins the painting shortly after it arrives. Fearing that he will lose his job and possibly face criminal charges for the damage, David becomes despondent and gets drunk, even though his family returns out of pity. To save his career, Bean sneaks back into the gallery, distracts the guard by lacing his drink with laxatives, and replaces the ruined painting with a poster. The plan proves a success, fooling everyone including Newton. Bean nearly panics when he realises he has to make a speech, but gives an improvised, sentimental and deep monologue about the painting that wins the crowd’s praise and approval.
Shortly after the speech, Bean is approached by Lieutenant Brutus, whom he crossed paths with, leaving David worried that he knows the truth about the priceless paintings mishap, only to learn from him that Jennifer was rushed to hospital after being involved in a motorcycle accident while with her boyfriend. Rushing to the hospital, David goes to be with his wife, leaving Bean to wander about the hospital’s reception area and be mistaken for an actual doctor after picking up a stethoscope that had been dropped. Forced into a surgery room, he finds himself coming across Brutus on the operating table, having been shot while dealing with a mugging, whereupon he manages to recover the bullet in his body via an unorthodox procedure. Leaving the police officer to recover, Bean ends up being mistaken by David for a doctor, who begs for his help, leaving him alone with Jennifer whom he revives from a coma, after he accidentally shocks himself with a defibrillator and lands on her. Grateful for having his daughter back, David is surprised to find his saviour to be Bean, who asks to stay another week with him.
Spending quality time with David’s family, Bean soon returns to the airport, thanking David for the time he spent, before returning to London. Once home, Bean admires his room, decorated with photographs of the Langley family, before taking a final look at the ruined, original Whistler’s Mother he smuggled back with him, and then going to bed.