The film opens with a nostalgic look back at Garfield’s home, showcasing heartwarming snapshots of his owner, Jon, as he shares moments with Garfield during his kitten days and as he matured into the charming, albeit lazy, cat we know and love. We soon find Garfield, voiced by Bill Murray, comfortably nestled in Jon’s bedroom, lounging in his cozy kitty bed alongside his beloved stuffed bear, Pooky. His tranquility, however, is short-lived as he decides to stir up some mischief by jumping onto Jon, who is in a deep slumber. With some cunning antics, he flushes the toilet to prompt Jon to leave the shower, making sure his breakfast is served promptly. Trade-offs ensue, as Garfield skillfully exchanges his liver-flavored cat food for Jon’s delectable tuna fish.
As the story unfolds, Garfield is seen idly lounging next to Jon's computer when a mouse swiftly scurries from under the desk. Jon yells at Garfield to capture the mouse, but our indifferent feline simply remains seated, prompting Jon to chase the mouse out with a broom. Outside, Garfield encounters Louis, his cheeky mouse friend, voiced by Nick Cannon. Their exchange reveals Louis’s dilemma of having to stay away when Jon is around, attributing this to the delightful allure of macadamia nuts. Garfield’s adventures take him through a series of interactions with a grumpy Doberman named Luca and the annoying yet cute cat, Nermal, not to mention his own grouchy disposition.
Later, Garfield becomes engrossed in a television show featuring the notoriously grumpy Happy Chapman, played by Stephen Tobolowsky, who, despite his allergic reactions to his feline counterpart, reaches out to cat lovers everywhere through his excessive advertising of cat food. In a delightful twist, Garfield learns that Jon, portrayed by Breckin Meyer, has returned home carrying multiple packages of lasagna, igniting Garfield’s gluttonous instincts as he devours the entire stash. However, the bliss is short-lived as Jon mentions a trip to the vet, with a familiar face—Liz Wilson, played by Jennifer Love Hewitt. Garfield, however, has his own agenda, teasingly suggesting that Jon should admit his long-held feelings for Liz, which he ironically seems to have harbored since their high school days.
At the veterinarian’s office, while Liz inquires into Garfield’s health, she also seizes the moment to probe Jon about his feelings, leading to a humorous misunderstanding where Jon confesses he is ready for a dog, much to Garfield's horror. This is the precipitating moment that brings Odie, the exuberant dog, into their lives. As chaos ensues at home with the spiraling presence of his new canine companion, Garfield is clearly not thrilled about sharing Jon’s affections with Odie. From dramatic encounters with Nermal to Garfield’s internal monologues about dogs, the tension escalates when Jon decides to accept an invitation to a dog show from Liz, prompting Garfield to break his “never leave the Cul-De-Sac” rule in a desperate bid to keep his place in Jon’s heart.
During the dog show, Garfield inadvertently wreaks havoc while Odie capably wows the judges with his tricks, earning him accolades and a blue ribbon. However, as Jon continues to bond with Odie, Garfield's jealousy intensifies. The culmination of these events leads to a chaotic night where Garfield, in a moment of reckless abandon, locks Odie outside, who then mysteriously disappears, leading to a frantic search from Jon and Liz. Unfortunately, Odie finds himself in the clutches of Happy Chapman, who sees the potential in showcasing Odie further away, darkening the thought of ever seeing his beloved owner again.
In a quest of redemption, Garfield hatches a plan to rescue Odie, leading him on a whirlwind journey into the bustling city, encountering whimsical rodents and navigating through the studio to thwart Chapman’s plans. The stakes rise as Garfield must charm and battle through various obstacles, including an infamous encounter with Animal Control. In the thrilling climax, with the help of fellow captured pets and some unexpected teamwork, Garfield's cleverness shines brightly, ultimately leading to an unforgettable showdown against Chapman.
After a night filled with drama and unexpected heroism, the story returns full circle back to Garfield’s home where love prevails, and the family finds comfort in each other’s company. In a closing moment of warmth, Jon and Liz share a quiet evening together with Garfield and Odie, as he muses about the newfound bond they share. Ultimately, Garfield learns that despite the changes in his life, there’s room for more love, laughter, and of course, lasagna.
