The film was theatrically released in the United States on June 7, 2019, by Universal Pictures. It received mixed reviews from critics and has grossed $422 million worldwide. Sometime after the events of the first film, Max and Duke's owner, Katie, gets married to a guy named Chuck and has a son, Liam, whom Max disapproves of at first due to his rough play but eventually softens up to him. Later, Max's overprotective feelings for Liam develop into an itch which prompts Katie to get him a dog cone from the veterinarian in an effort to lower his symptoms. Max's luck changes when Duke reveals that the family is going on a road trip outside of the city.
When Max and Duke's family reaches a farm owned by Chuck's uncle, Max grows unaccustomed to the farm's ways, including local sheepdog Rooster. After an incident with the farm's sheep, Rooster takes Max out to find one of the missing sheep that ran away. Rooster's teaching and encouragement to Max about acting unafraid prompts Max to successfully retrieve the sheep. Rooster allows Max to stay with him overnight as a result. Before departure, Rooster also gives Max one of his handkerchiefs as a souvenir. Before Max left, he had entrusted his favorite toy, Busy Bee, to Gidget. Unfortunately, Gidget loses Busy Bee in a cat-infested apartment owned by a cat lady. She receives cat lessons from Chloe, Mel, Buddy, and Sweet Pea in order to sneak in the apartment easier. With the help of Norman, she successfully retrieves Busy Bee and unintentionally gets hailed as the "queen of cats". Meanwhile, Chloe and Snowball meet Shih Tzu Daisy, who explains that she needs Snowball, who dreams of being a superhero, to assist her with rescuing a White tiger cub named Hu. While on flight back to the city, Daisy encountered him being held captive by an abusive circus owner named Sergei.
Daisy and Snowball sneak in and find the circus Hu is in. With much difficulty from Sergei's black wolves, they free Hu from the circus. However, in the heat of the escape, Daisy accidentally drops her flower clip, which the wolves use to track her down. She and Snowball take him to Pops' apartment first. Pops reluctantly lets Hu live there at first, but due to his destruction of the apartment afterwards, Hu is kicked out and relocated in Max and Duke's apartment. Around the same time, the family returns from the trip.
Sergei and his wolves track Daisy down and capture both Hu and Daisy..