A girl named Penny and her extraordinary dog, Bolt, who possesses incredible superpowers, must constantly thwart the evil schemes devised by the devious Doctor Calico. However, unbeknownst to Bolt, he is merely a star on a popular TV series titled Bolt. To enhance the illusion for their star, the producers have kept Bolt in the dark, ensuring that he believes the show is real and that he truly has superpowers.
After the latest episode wraps up, Bolt, believing that Penny has been abducted by the show's villain, makes a daring escape from his trailer. In a clumsy attempt to break through a window, he knocks himself unconscious and tumbles into a box of styrofoam peanuts. Completely unaware of Bolt's presence, the box gets shipped all the way from Hollywood to New York City.
In the bustling streets of New York, Bolt encounters Mittens, a streetwise female cat who has a knack for bullying pigeons out of their meals. Convinced that Mittens is an evil adversary working for Doctor Calico, Bolt forces her to join him on his quest back to Hollywood. Their adventure begins as they hitch a ride on a truck headed westward.
Meanwhile, back in Hollywood, Penny, portrayed by [Susie Essman], is despondent over Bolt’s sudden disappearance. Despite her grief, the studio pressures her to continue filming with a Bolt imposter. As Bolt and Mittens journey together, Bolt begins to notice the waning of his supposed superpowers. He rationalizes that this decline is due to the styrofoam's effect on him. For the first time, he experiences feelings of pain and hunger, and Mittens teaches him how to behave like a loveable, needy dog, which earns him food.
Their group soon expands with the addition of Rhino, a brave hamster and devoted fan of Bolt. Despite Mittens' insistence that his superpowers are just an illusion, the conversation is interrupted when Animal Control arrives, capturing them and taking them to an animal shelter. Fortunately, they are saved by Rhino during their transport. It is in this moment that Bolt comes to a painful realization that he is just an ordinary dog. However, after an encouraging pep talk from Rhino, he finds a renewed sense of confidence.
As they escape the shelter, Bolt discovers the joys of typical dog life, such as hanging his head out of a window and playing fetch. However, Mittens grows apprehensive and reveals she will not accompany him beyond Las Vegas. Confessing her belief that his life in Hollywood is merely a façade, she shares her own traumatic tale of abandonment, which makes Bolt more stubborn in his quest. Despite her heartfelt outburst, Bolt remains determined to reunite with Penny and continues on without her.
Seeing Bolt leave, Rhino persuades Mittens to help find him once again. After a series of misadventures, Bolt arrives at the studio and finds Penny in a warm embrace with his lookalike. Unfortunately, unaware of her true feelings, Bolt departs in heartbreak, thinking she no longer cares for him. Meanwhile, Mittens witnesses Penny confiding in her mother, expressing how much she misses Bolt and loves him. With this epiphany, Mittens rushes after Bolt, hoping to clarify the misunderstanding.
In a dramatic turn of events, as filming proceeds, the lookalike's mishap with some torches ignites a fire on the sound stage, trapping Penny inside. Bolt, with his instincts kicking in, rushes back and reunites with Penny amidst the chaos, fighting to save her from smoke asphyxiation.
After these harrowing events, Penny, along with her mother, takes a stand against their agent's attempt to exploit the situation for publicity, ultimately quitting the show. Penny adopts both Mittens and Rhino, trading the chaos of Hollywood for a simpler life in the countryside, where she can cherish her time with Bolt and her newfound pets. Although the show continues without her, with a ridiculous storyline involving facial reconstruction and alien abductions, Bolt’s genuine story remains close to Penny’s heart.
