Elliot has grown giant new antlers and is getting married to Giselle. But during a mishap, Elliot's new antlers are cracked off and now look like they did in the first film, which upsets him. Luckily, Boog and the others manage to cheer Elliot up by having a rabbit fight. But Elliot has new emotions about his marriage and feels reluctant to marry Giselle. Mr. Weenie finds a dog biscuit trail that his previous owners left behind and uncontrollably follows it. At the climax of the wedding, Elliot witnesses Mr. Weenie being taken away by his old owners, Bob and Bobbie. Elliot tells the story to the other forest animals (a little overreacting) and decides to make a rescue mission to save him. The other ones that go on Elliot's rescue mission are Boog, Giselle, McSquizzy, Buddy, and Serge and Deni.
Meanwhile, the other pets meet. There is Fifi, a toy poodle and his basset hound companion Roberto, two cats named Stanley, whose companion is a mentally retarded cat named Roger, and a Southern dog named Rufus, whose companion is his girlfriend Charlene. Fifi discusses his hatred for wild animals as one night he goes into the bushes to retrieve his chew toy and is shocked by the wild animals inside, and accidentally gets his tail touched by the bug lighter. He then tries to maul a nearby rabbit, until stopped by his owner. Meanwhile, the wilds find Weenie, much to Elliot's dismay, who does not want to marry Giselle. They try to free him while his owners are in a gas station. They free him from his chains, but accidentally leave him stuck on the RV along with Buddy. Elliot and Giselle get in a feud, and eventually leaves Elliot to search for Mr. Weenie himself, while Serge and Deni fly to look for him.
The owners reach the pet camp with Mr. Weenie and Buddy, unbeknownst to them. The other pets meet with Weenie, and Fifi tries to change Weenie back into a pet, but fails. Buddy helps Weenie escape and Buddy tries to free Weenie from his shock collar. During the chase, Fifi gets shocked by the collar and gets his forehead burned, which causes him to lose most of his sanity. Meanwhile, Serge and Deni return and explain they found Weenie and Buddy at a pet camp, which they now escaped from. Boog and the others set camp at a human camp, and Boog tries to convince Giselle that Elliot is a good person and they are good together, but fails. Elliot, meanwhile, is having a horrible time, following his own tracks that he confuses for Mr. Weenie's and gets his head stuck on a trash can lid with gum on it, but misses his friends and becomes a mess. The wilds reach the pet camp, but the pets and their owners have already left, but realizes that they have gone to Pet Paradiso, a vacation spot for pets. Elliot finds Weenie and Buddy and is convinced to go to Pet Paradiso to save his friends.
The wilds reach Pet Paradiso and try to sneak in by disguising themselves as pets, with Giselle as a Dalmatian and McSquizzy as a chihuahua. Boog attempts to sneak in as a cat, but gets the idea to be a sheepdog. Elliot also disguises himself as Boog's female human owner. Giselle and McSquizzy walk around Pet Paradiso looking for Mr. Weenie, but their cover is blown and are kidnapped by Fifi and the other pets. Elliot, Boog, Buddy and Mr. Weenie attempt to go inside to save Giselle and McSquizzy, but are captured by Fifi as well. Fifi tries to kill them with a pile of shock collars. As Boog tries to stop Mr. Weenie from going down a waterslide, his cover is blown as well and the security try to tranquilize him after he causes a rampage after people confuse his weight. Before Fifi shocks the wilds into submission, Elliot tries to profess his love for Giselle, but fails. As Fifi is about to fry the wilds, Boog, is was chasing Weenie down a waterslide, enters the pets' lair, and the water that was rushed from the waterslide forces everyone out of the lair.
A battle between the wilds and the pets ensues, with the Pet Paradiso security focused on tranquilizing the wilds. Elliot saves Giselle and accidentally places all the shock collars on himself. He also wrestles Fifi in the pool for the shock collar remote. Fifi eventually grabs the remote and activates all the shock collars, but does not realize that Elliot put all the shock collars on him. Fifi survives, but the explosion caused him to lose his hair and become bald. The pets and the wilds settle their differences and decide to become friends. Mr. Weenie decides to join the pets and returns to his owners in rejoice. Elliot finally professes his true feelings for Giselle, and they get married.
- Joel McHale as Elliot, the deuteragonist.
- Mike Epps as Boog, the main protagonist.
- Cody Cameron as Mr. Weenie
- Jane Krakowski as Giselle, the tritagonist.
- Billy Connolly as McSquizzy, the secondary tritagonist.
- Crispin Glover as Fifi, the main antagonist.
- Danny Mann as Serge
- Matt Taylor as Deni / Buddy / Ian
- Steve Schirripa as Roberto, the secondary antagonist.
- Fred Stoller as Stanley, one of the tertiary antagonists.
- Sean Mullen as Roger, one of the tertiary antagonists.
- Diedrich Bader as Rufus, one of the tertiary antagonists.
- Olivia Hack as Charlene, one of the tertiary antagonists.
- Jacquie Barnbook
- Dana Belben
- Jeff Bennett
- Ranjani Brow
- June Christophter
- David Cowgill
- Rachel Crane
- Omar Crook
- Lauri Fraser
- Elisa Gabrielli
- Nicholas Guest
- Bridget Hoffman
- Wendy Hoffmann
- Walter Jones
- Scott Menville
- Kevin Michael Richardson
- Matt Taylor
- Hans Tester
- Peter Lord
- David Sproxton
Sony announced a sequel to Open Season in September 2007. Although, the original grossed $85 million and $105 million outside the United States, Sony felt the film performed much better on DVD, thus, making a direct-to-DVD sequel. Sony Pictures Digital president said that "the studio will keep Open Season 2's costs low by utilizing Imageworks' satellite facilities in India and New Mexico".
Rotten Tomatoes shows Open Season 2 as having only a 44% viewer rating, which is considered "rotten."
Although Open Season 2 was as direct-to-video in the United States and the United Kingdom, it was released theatrically in some countries. In South Africa on its opening day, the film grossed $84,244 from 26 screens with an $2,081 average. In Russia, it opened with $2,835,600 from 360 screens with a $7,877 average. In Poland, it opened with $194,339 from 75 screens with an $2,591 average. In total, the film grossed $8,716,950.
- Open Season is the first Sony Pictures Animation film to become a franchise, followed by The Smurfs.
- It was also the first direct-to-video sequels to be produced by Sony Pictures Animation.