In a snug fir tree home, three chipmunk friends—Alvin, Simon, and Theodore—are left to navigate life on their own after their parents depart. Their serene existence takes an unexpected turn when their tree is cut down and shipped to Los Angeles, where it transforms into a stunning Christmas tree for JETT Records. Concurrently, struggling songwriter Dave Seville, who dreams of success, faces the harsh reality of rejection from his former college mate turned executive, Ian Hawke. Ian's cruel suggestion to abandon his writing dreams leaves Dave disheartened.
As fate would have it, the Chipmunks stumble upon a basket of muffins that Dave had discarded and follow him to his home. At first, Dave is oblivious to their presence, but when he finally discovers them, he tries to shoo them away. However, after witnessing their magnificent renditions of "Only You (And You Alone)" and "Funkytown," he finds himself enchanted by their talents. Dave proposes a mutually beneficial arrangement: the Chipmunks would perform his songs in exchange for food and shelter. Inspired by their soothing chirps during the night, Dave creates a new song for them, titled "Christmas Don't Be Late."
The following day, filled with excitement, Dave presents the Chipmunks to Ian, but their performance is marred by stage fright. Matters worsen as Dave loses his advertising job because the Chipmunks took too many liberties with his presentation. As life unfolds, Dave invites Claire, an old flame, over for dinner, leading to an awkward evening when Alvin attempts to set a romantic mood, causing Claire to feel uncomfortable and leave.
Seeking redemption, the Chipmunks visit Ian at his lavish home and impress him with their version of "Christmas Don't Be Late," leading to a record deal and the revival of Dave's songwriting position at JETT. However, as the Chipmunks' fame grows, Dave becomes increasingly troubled by the pressures they face. Misled by Ian into believing that Dave is a hindrance, the Chipmunks choose to abandon Dave to join Ian on a demanding nationwide tour. During this exhausting adventure, Ian exploits their naivety, pushing them beyond their limits.
When news breaks of Ian's plan for a twelve-month global tour, Dave decides it's time to rescue the Chipmunks during their concert at the Orpheum Theatre. As the dramatic finale approaches, a wise veterinarian reveals to Ian that the Chipmunks' voices have suffered from overwork, and they need a break. Unfazed by canceling the concert, Ian urges the trio to lip-sync to maintain appearances. However, with help from Claire, Dave infiltrates the event and, upon hearing his father’s voice, the Chipmunks uncover Ian's deceit and devise a plan to create chaos on stage.
When security moves to apprehend Dave, Ian seizes the moment to cage the Chipmunks, ready to whisk them away on tour. Dave appeals to Ian, emphasizing the Chipmunks’ need for real-life experiences, but Ian remains unmoved. In a twist of fate, Dave escapes in his limousine while being chased by Ian. Once Ian loses track of him, the Chipmunks appear in Dave's vehicle, paving the way for a heartfelt reconciliation between them. Yet, Ian's realization of their escape comes with a heavy price: he is left with nothing, forced to confront the consequences of his relentless ambition.
