Bilbo and the Dwarves watch from the Lonely Mountain as the dragon Smaug sets Laketown ablaze. Bard breaks out of prison, and eventually kills Smaug with the black arrow brought to him by his son Bain. Smaug's falling body crushes the fleeing Master of Laketown and his cronies, who were escaping on a boat laden with the town's gold. Bard reluctantly becomes the new leader of the people of Laketown as they seek refuge in the ruins of Dale, while Legolas travels to investigate Mount Gundabad with Tauriel. Thorin, now struck with "dragon sickness" over the vast treasure in the mountain, searches obsessively for the Arkenstone, which Bilbo had previously found but kept hidden. Thorin, hearing that Laketown survivors have fled to Dale, orders the entrance of the Lonely Mountain sealed off.
Meanwhile, Galadriel, Elrond, and Saruman arrive at Dol Guldur and free Gandalf, sending him to safety with Radagast. They battle and defeat the Nazgûl and a formless Sauron himself, banishing them to the East. Azog, marching on Erebor with his vast Orc army, sends his son Bolg to Gundabad to summon their second army. Legolas and Tauriel witness the march of Bolg's army, bolstered by Orc Berserkers and giant bats.
Thranduil and an elf army arrive in Dale and form an alliance with Bard in order to reclaim a treasure once withheld from them by Thrór. Bard goes to the mountain and asks Thorin for the share of gold that he had previously promised the people of Laketown, but Thorin refuses. Gandalf arrives at Dale to warn Bard and Thranduil of the threat posed by Azog, but Thranduil dismisses him. Bilbo sneaks out of Erebor to hand the Arkenstone over to Thranduil and Bard so that they can trade it for the gems and gold they were promised and prevent a battle. When Bard's and Thranduil's armies gather at the gates of Erebor, offering to trade the Arkenstone for the promised treasures, Thorin angrily refuses to believe they have the Arkenstone until Bilbo admits giving it away and chides Thorin for letting greed cloud his judgement. Outraged by what he sees as betrayal, Thorin nearly kills Bilbo, but Gandalf arrives at the gate and shames Thorin into releasing Bilbo. Thorin's cousin Dáin arrives with his Dwarf army, and a battle of Dwarves against Elves and Men begins, until Wereworms emerge from the ground, releasing Azog's army from their tunnels. With the Orcs outnumbering Dáin's army, Thranduil and Bard's forces, along with Gandalf and Bilbo, join the battle. However, a second front is opened when many Orcs, Ogres, and Trolls attack Dale, forcing Bard to withdraw his forces to defend the city.
Inside Erebor, Thorin suffers traumatic hallucinations before regaining his sanity and leading his company to join the battle. He rides towards Ravenhill with Dwalin, Fíli, and Kíli to kill Azog; Bilbo follows them using his magic ring to move through the combat unseen. Meanwhile, Tauriel leaves with Legolas following her to warn the Dwarves of Bolg's approaching army. Fíli and Kíli are captured, and Azog kills Fíli as Bilbo and the other Dwarves are forced to watch. As Thorin engages Azog in a fight to the death, Bolg knocks Bilbo unconscious, overpowers Tauriel and then kills Kíli, who had come to her aid. Legolas battles Bolg and eventually kills him. Thorin kills Azog, but is fatally wounded in the process. The Great Eagles then arrive with Radagast and Beorn to fight the newly arriving Orc army, and the Orcs are finally defeated. Bilbo regains consciousness and makes peace with the dying Thorin. Tauriel mourns Kili, and Thranduil acknowledges their love. Legolas then tells Thranduil he must leave, and Thranduil advises him to seek out a Dunedain ranger in the north who goes by the name "Strider".
Bilbo bids farewell to the remaining members of Thorin's company and journeys home to the Shire with Gandalf. As the two part ways on the outskirts of the Shire, Gandalf admits his knowledge of Bilbo's ring and warns him that magic rings are not to be used lightly. Bilbo returns to Bag End to find his belongings being auctioned off by his least favourite relatives, the Sackville-Bagginses, because he was presumed dead. He cancels the sale, but finds his home pillaged. He starts to tidy up and takes the Ring out of his pocket. Sixty years later, Bilbo receives a visit from Gandalf on his 111th birthday.
- Thomas, Twilight Sparkle, Percy, Pinkie Pie, James, Rarity, Gordon, Rainbow Dash, Henry, Fluttershy, Toby, Applejack, Edward, Emily, Bill and Ben, Bertie, Terence, The Logging Locos (Bash, Dash and Ferdinand), Stephen, Luke, Spike, The Cutie Mark Crusaders (Apple Bloom, Sweetie Belle and Scootaloo), Princess Cadance, Shining Armor, Theodore Tugboat, Hank, Emily, George, Foduck, Princess Celestia, Princess Luna, Barret Barricade, Sunset Shimmer, Knockout, Puffer, Dolphy, Rachel, Mighty Joe, Daylight, Jenny, Pete, Kevin, Morley, Blitzer, Tempest Shadow, Grubber, Songbird Serenade, Capper, Captain Celaeno, Princess Skystar, Queen Novo, Ed, Edd, n Eddy, Cinderella, Dawn, Manaphy, Gordon Quid, Waffle, Mr. Blik, Doug Funnie, Skeeter Valentine, Roger Smith, Bender Bending Rodríguez, Minerva Mink, Master Shake, Meatwad, Frylock, Pazu, Sheeta, Wubbzy, Widget, Walden, Daizy, Natsu Dragneel, Lucy Heartfilia, Gray Fullbuster, Erza Scarlet, Wendy Marvell, Happy, Carla, Babs Seed, Coco Pommel, Cheese Sandwich, Maud Pie, Belle, Ariel, Princess Jasmine, Jenny Foxworth, Princess Anna, Elsa the Snow Queen, Mulan, Pocahontas, Esmeralda, Snow White, Princess Aurora, Alice, Judy Hopps, and Nick Wilde guest star in this film.
- Ernie the Giant Chicken, Sideshow Bob, R2-Q5, Bobby Briggs, Sheriff Nichols, James Woods, Hunter J, Attila and Hun, Team Galactic (Mars, Jupiter and Saturn), The Dazzlings, Diesel 10, Splatter and Dodge, Diesel, Trixie, Gilda, Lightning Dust, Diamond Tiara, Silver Spoon, Starlight Glimmer, Suri Polomare, Dawn Bellwether, Nightmare Moon, King Sombra, Discord, and Queen Chrysalis will work for Azog in this film.
- The storyline continues in Brian and the Eeveelution Family's Adventures of The Lord of the Rings: The Fellowship of the Ring.