Movie begins with Garfield being abandoned by dad, only to find a lonely Jon and become his pet. Cut to montage of him living like a king with John, the adoption of Odie, and him using Odie as a servant.
Garfield and Odie then get captured by two dogs who tie them up in an abandoned mall. Garfield’s dad Vic then saves them. Afterwards, the villain, a white cat named Jinx, reveals herself. She was an old partner of Vic who got sent to the pound during a milk heist and now wants revenge of Vic by making him collect a bottle of milk for every day he she was in the pound, and she forces Garfield and Odie to join because.
The group decides to raid the old family farm Vic left Jinx at, only to realize it has been bought out by a mega-corp who have upped security. In realizing this, the group find Otto, the old mascot for the farm, recently going through a depression after being exiled. They learn that the mega-corp split up him and his love, Ethel, so they join forces to get the milk and Ethel.
Training ensues, and Vic and Garfield come to an emotional breakthrough as Vic never left Garfield, he was just waiting for a chef at the pizza place to get off a phone call so he can loot the trash and get baby Garfield some food. By the time he gets back, Jon already took in Garfield, so Vic decides to let Jon raise his kid.
After breakthrough, it is heist time. During the heist, they go up against Marge, who is basically a poor man’s Dubois (Madagascar 3). Anyway, Jinx alerts Marge ahead of time as she just wanted to get Vic sent to the pound. Vic bails on his kid and completes the milk mission while leaving Garfield, Odie and Otto behind.
At the pound, Garfield gets rescued by Jon, but not before the cats, associated with Vic, speak about his father bailing during heists to watch Garfield at dinner time in a tree across the street. Garfield finds the tree and the emotional moment occurs as Garfield sees all the tics his farther carved into the tree to count all the times he visits. Vic left Garfield and Odie as he knew Jon would get them, whereas Jinx would kill them if brought along.
Garfield then goes to save his dad from Jinx who is about to throw him off a train, off a bridge, into a pit of spikes. Garfield uses the skills his dad taught him plus drone pizza deliveries, established in intro, to save his dad, but they mess up and still get caught. Randomly, because they are at peace when faced with death, Jinx two henchmen decide they cannot kill them and turn on the cat.
Movie ends with the Garfield giving Jinx to Marge in exchange for Ethel. The two hench dogs now work for Marge, and Garfield brings his father into his life with Jon.
Second movie teased at end credits…