Five years after the Battle of Chicago, humanity has grown fearful of the Transformers, resulting in the termination of joint operations with the Autobots. Cemetery Wind, an elite CIA black ops unit, formed by opportunistic agent Harold Attinger and team leader James Savoy, (who Mojo Jojo, The Rowdyruff Boys, Le Quack, Katz, Big Toe, Phineas T. Ratchet, Madame Gasket [lead by Bradey O'Diesel] are working for) is tasked with hunting the remaining Decepticons. However, they have also been secretly hunting Autobots, believing all Transformers to be a threat, despite the Autobots officially being granted sanctuary by the government. With help from the Cybertronian bounty hunter Lockdown, they ambush and brutally kill Ratchet. However, their primary target is Optimus Prime, whom Lockdown wants captured alive. Meanwhile, Bradey O'Diesel has gathered up many of the villains, and she thanks them for their help in her plans to take over the world.
In rural Texas, Cade Yeager is an inventor struggling financially, with college funding for his daughter, Tessa, and the loss of his property looming. (whom our heroes are with) One day he and his friend Lucas buy an old truck to repair and sell. Cade discovers that the truck is an injured Optimus Prime and repairs him, bringing him back to life.
After locating Optimus in Texas, Cemetery Wind and Lockdown (along with Gremlin and Pacer) confront and threaten the Yeagers and Lucas before Optimus attacks and rescues them. Cade, Tessa and Lucas escape with Tessa's secret boybuddy, Shane Dyson. As Hiccup, Toothless, their friends, Finn McMissile, and Holley Shiftwell arrive too. Safety is found after a long chase, but Lucas is killed by one of Lockdown's grenades. Tensions rise between Cade and the two lovers over their secret relationship while Optimus rallies remaining Autobots Bumblebee, Hound, Drift, and Crosshairs. Cade hacks into a spy drone he took from the Texas attack, learning of Kinetic Solutions Incorporated, a technology firm in league with Cemetery Wind, and they decide to infiltrate KSI HQ in Chicago.
Meanwhile, Joshua Joyce, the head of KSI, shows Darcy transformium, the scarce metal of which Transformers are made. He has imprisoned Brains to decode dead Transformers' minds and utilize their data for human-created Transformers "upgrades". Joshua shows Darcy his prized creation Galvatron, created using data from Megatron's severed head. But also inside the facility, is the Idominous Rex! (who the villains have resurrected and have been training to send after the Eds, Thomas, Twilight, and the team). The Autobots and our heroes storm the facility, but Joshua stops them, proclaiming the Autobots are no longer needed now that they can create their own Transformers. Disillusioned, the Autobots decide to leave.
Forced by Attinger, Joshua launches Galvatron and Stinger (a man-made Transformer similar to Bumblebee) while the villains send out the I-Rex to pursue the Autobots. Optimus fights Galvatron before Lockdown wounds him, capturing him and Tessa on his ship. He explains that those who made the Transformers, the "Creators," want Optimus back. Before leaving, Lockdown gives Cemetery Wind a device called the Seed, which when detonated transforms living things into transformium, giving the Autobots time to board the ship. And everyone splits up to find Optimus. Cade and Shane save Tessa and escape with Bumblebee while the others save Optimus and escape on a detachable ship. Optimus and Brains reveal that Galvatron is a reincarnated Megatron who has manipulated KSI to steal the Seed and rebuild the Decepticons. While the Eds explain to the dragon riders of Berk about the I-Rex. Cade warns Joshua, who retreated to Beijing to use production facilities, about Galvatron and Attinger. Joshua backs off his deal with Attinger while Galvatron activates himself and infects all the KSI prototypes. Joshua flees with the Seed to Hong Kong, with Attinger and Galvatron chasing him. On the way to Hong Kong, everyone lock and loads all their weapons and are ready for battle. But then Pinkie accidentally makes her revolver go off, the bullet ricocheting around them and causing them to seek refuge under a table.
When the Autobots try to retrieve the Seed at Hong Kong, their ship is shot down by the Decepticons, leaving the Yeagers, Shane, Hound and Bumblebee to fight. Cade kills Savoy in a fist fight, but the Decepticons outnumber the Autobots. Knowing this, Optimus releases and tames the Dinobots. With their help, the Autobots defeat the Decepticons. Through the intense Battle, Toothless uses one of his stronger plasma blasts to blow the Rowdyruff Boys revert back to their snips, snails and puppy-dog tails. However, Lockdown returns with a magnetic weapon to reclaim Optimus and the Dinobots. After Optimus destroys the magnetic weapon, he fights Lockdown. He then saves Cade by killing Attinger, who held them at gunpoint. However, Optimus is immediately impaled by Lockdown with his sword to a wall. As Cade and Bumblebee fight Lockdown, Tessa and Shane use a tow truck to pull the sword out of Optimus, who then kills Lockdown. Then Katz, the Clutching Foot, and Le' Quack beat up Courage and are to finish him off when Toothless blows a gigantic hole under them, sending them to their doom.
But then the I-Rex goes to kill the team until the dragons battle it, but the hybrid dinosaur is too much for them, then suddenly Rexy appears! And they both battle and the I-Rex almost wins when Blue appears and helps battle it. Together the 2 dinosaurs and the dragon knock the I-Rex closer to the sea where a crocodile headed Sea Monster grabs the I-Rex and drags it into the sea. Then the dragons help Rodney destroy Ratchet's sweepers and then cause Gasket to fall into a smelter's furnace while Ratchet is bonded into chains hanging from a metal pole. They defeat the remaining Decepticons as Galvatron and the remaining villains retreat.
The Dinobots go free as Joyce plans to make amends with Cade by arranging for him and Tessa to gain a new house. Optimus then flies into space with the Seed, sending a message to the Creators that he is coming for them.
- The Powerpuff Girls (Blossom, Bubbles, and Buttercup), Courage the Cowardly Dog, Norbert and Dagget, Rodney Copperbottom, Fender Pinwheeler, Wonderbot, Piper Pinwheeler, Crank Casey, Lug, Diesel, Lazlo, Raj, Clam, Hiccup, Toothless, Astrid, Stormfly, Snotlout, Hookfang, Fishlegs, Meatlug, Ruffnut and Tuffnut, Barf and Belch, Catdog, Steamy, Puffy, Evan, Shai-Shay, Rodger the logging loco, Rattlesnake Jake, 1206, Socky, Skunky, J.J., Buzz, Mako, Sharky, Willy, Mr. Great White, The Miner Trains, The Planet Trains, T.C., Hugs, Sherin, Marshall P.F., General Dedrich, The Trolley Fighters, Timber, Splinter, Chomper, Whiffle, Falcon, Jenny Wakeman, Danny Phantom, Dudley Puppy, Kitty Katswell, Inspector Gadget, Thomas, Twilight Sparkle, Percy, Pinkie Pie, Toby, Applejack, James, Rarity, Gordon, Rainbow Dash, Henry, Fluttershy, Edward, Emily, Hiro, Charlie, The Logging Locos (Bash, Dash and Ferdinand), Spike, The Cutie Mark Crusaders (Apple Bloom, Sweetie Belle and Scootaloo), Button Mash, Babs Seed, Skarloey, Rheneas, Sir Handel, Peter Sam, Rusty, Duncan, Luke, Shining Armor, Princess Cadance, Princess Celestia, Princess Luna, Daring Do, Maud Pie, Bill & Ben, Bertie, Terence, Stephen, Theodore Tugboat, Hank, Emily, George, Foduck, Spencer, Duck, Donald and Douglas, Oliver, Toad, Victor, Kevin, Zecora, Team Chugger, Finn McMissile, Holley Shiftwell, Mordecai, Rigby, Skips, Benson, Pops, Muscle Man, Hi Five Ghost, Margaret, Eileen, Dusty Crophopper, Ishani, The CyberSquad (Matt, Jackie, Inez, and Digit), Wreck-It Ralph, Vanellope von Schweetz, Fix-It Felix, Jr., Sergeant Calhoun, Merida, Mulan, Mushu, and Criki guest star in this film.
- Bradey O'Diesel, Mojo Jojo, The Rowdyruff Boys, Le Quack, Katz, Big Toe, Phineas T. Ratchet, Madame Gasket, the Indominus Rex, Diesel 10, Diesel, Splatter and Dodge, Den, Dart, Ripslinger, Ned and Zed, Nightmare Moon, King Sombra, The Nightmare Train, The Evil Mane 6, Discord, Queen Chrysalis, Professor Z, Gremlin and Pacer, The Lemon Cars, Trixie, Diamond Tiara, Silver Spoon, Hacker, Buzz, Delete, Dr. Claw, Biff and Tiff, DOOM, The Chamoleon, and Morack will work for Harold Attinger in this movie.
- Transformers: Age of Extinction, Thomas & Friends: Tale of the Brave, and How to Train Your Dragon 2 were all released in 2014.
- The Storyline concludes in Ed, Edd, n Eddy's Ed-ventures of Transformers: The Last Knight.
- Tuffnut and Lucas Flannery are both portrayed by T.J. Miller.
- Rexy and Blue make a climax appearance in this film.
- Despite not singing a song in the film, this film will be dedicated to Chester Bennington who sang songs for the first three films.
- Film Opening
- Bradey's villain meeting
- Cade Yeager/Ratchet's death
- Cade's discovery/Optimus Prime awakes
- Cemetery Wind Car Chase
- Meeting up with the remaining Autobots
- KSI Industries
- Sneaking into the industries/Attack at the industries
- Freeway chase/Optimus vs. Galvatron/Lockdown captures Optimus
- On Lockdown's ship
- The Story of the Seed/The Eds' story of the I-Rex
- To Hong Kong!/Galvatron rises
- At Hong Kong/James Savoy's Death
- Battling the KSI Robots and Bradey's Army/Dinobots unleashed!
- Lockdown returns/Attinger's Death/Optimus vs. Lockdown
- Good vs. Evil
- Battling the I-Rex
- Confrontation with Bradey
- Farewell to Optimus/End of Film
- Epilogue: Bradey's repairs/Bradey's new partner
- The Delta Force theme (during the Cemetery Wind Car chase)
- (during the highway chase)
- (during the story of the I-Rex)
- I'll Make Man Out of You - General Dedrich