In Smurf Village, the Smurfs live peacefully among themselves and their leader is Papa Smurf. Some of the Smurfs include Clumsy Smurf, Brainy Smurf, Hefty Smurf and Smurfette, who was created by Gargamel from a lump of clay, but redeemed by Papa Smurf and became part of the village. Gargamel makes it his mission to capture the Smurfs, steal all of their essences, and become the most powerful wizard in the world.
After Smurfette accidentally breaks an invention by Brainy, she sees a blue creature hidden by a leaf and follows it straight into the Forbidden Forest, believing the creature to be a Smurf. She loses sight of the creature but discovers a hat was dropped by the possible Smurf. Smurfette ends up being captured by Gargamel and at his castle, she ends up inadvertently revealing the hat, enabling Gargamel to mix up a brew that causes him to locate the village on a map. Soon enough Hefty, Brainy, and Clumsy help Smurfette escape and return to Smurf Village, where Papa Smurf punishes them for disobeying his orders and confines them to their houses while dismissing their claims of a lost village filled with Smurfs.
Smurfette sneaks out into the night, however, with Brainy, Clumsy, and Hefty volunteer to come with her. Smurfette agrees to let them join her and together the four enter the Forbidden Forest. Gargamel soon discovers them trying to find the lost village and heads out with Azrael and Monty to stop them.
The four follow the map and end up in various adventures; after setting sail on their handmade raft along the river, they encounter Gargamel, Azrael, and Monty again. Following a brief chase, Gargamel is thrown out of his own raft, so Hefty and Smurfette convince the others to help save him. They do so, but instead of thanking them, he pushed them out of their raft, leaving them to plunge down a waterfall.
Meanwhile, back at Smurf Village, Papa Smurf tries to reconcile with Smurfette over his actions on the previous night but soon discovers she, Brainy, Hefty, and Clumsy are gone, so he sets out to find them and set things right with them. The four are soon captured by the leaf-covered creature along with a few others who reveal themselves to be female Smurfs. They are taken to Smurfy Grove where they meet Smurf Willow, Smurf Storm, Smurf Blossom, Smurf Lily and Smurf Melody, who all welcome the Smurfs to their humble home. Smurf Storm and Clumsy head away from the village to locate Gargamel and alert the others.
After a while of showing them what they do, Smurf Storm and Clumsy come back with her telling Smurfette was created by Gargamel. The female Smurfs prepare an attack that night but instead of Gargamel, Papa Smurf appears, and the female Smurfs accept him into their home. Soon, Gargamel comes and destroys Smurfy Grove, capturing all the Smurfs, with the exception of Smurfette, who is now alone, feeling heartbroken for her actions. However, Snappy shows her a picture of her and the others, and she soon realizes she is not a real Smurf, and heads back to Gargamel’s lair, then save the Smurfs.
At Gargamel’s lair, Brainy makes a plan to escape. Papa Smurf hears their plan and he and Smurf Willow decide to help them. Hefty, Brainy, Clumsy, and some of the female Smurfs succeed at the plan until Gargamel and Azrael spot them and put some of the female Smurfs and Clumsy into his Smurfilator, extracting their essence. Smurfette appears, tricking Gargamel into believing she wants to be an evil smurf again. When Gargamel tries to turn Smurfette into an evil smurf, he realizes Smurfette is absorbing his magic powers instead after destroying Brainy’s invention. The lair explodes, sending the trio back into the piranha-infested lake. Unfortunately, Smurfette has reverted to a lifeless lump of clay.
Back at Smurf Village, all the Smurfs mourn the loss of Smurfette. Their energy and love for Smurfette revives her, and everybody happily celebrates. Smurf Village and Smurfy Grove rejoice in their new unity; in the end, Smurfette finally finds her purpose and becomes most of all, a true-blue Smurf.