- For the theme song of the show, see Welcome to LazyTown (song).
"Welcome to LazyTown" is the first aired episode of LazyTown. It is an introduction to the titular community and the main characters.
"Stephanie arrives for the summer, staying with her Uncle Milford. She meets the kids of LazyTown and hears about their very own superhero, Sportacus. Meanwhile, Robbie Rotten attempts to put Sportacus out of commission in various ways, the last of which is a big hole, which Bessie falls into by mistake! It's up to Stephanie to rally her new friends, and it's up to Sportacus to save the day."
Night turns to day outside a large, blue airship. The inhabitant of the airship reveals themselves to be a man dressed entirely in blue and white as he flips out of bed, steps on a pad to put away the bed and does a one-armed push-up, all the while keeping his face hidden from the camera. The mystery man flips again so that he is standing on another pad that draws out a food table. The man in blue picks up a carrot stick before flipping over the table, landing on his feet to reveal a crest with a number 10 emblem on it.
Meanwhile, Mayor Meanswell is cleaning his office in the town hall while Miss Busybody is gossiping on the telephone. After inquiring, she learns that the Mayor's niece, Stephanie will arrive today. She is worried about the child-rearing skills of the Mayor, but he is not too worried since children only play video games and eat candy all day. Not convinced, Miss Busybody offers to help out. We change to Robbie Rotten's lair where he is making a cake before taking a peek using his periscope. All is quiet, just as he likes it.
As the Mayor is waiting for Stephanie, she walks into town quietly onto a worn basketball court, carrying two suitcases and a backpack. Nobody appears to be there. Using his periscope, Robbie notices Stephanie and the mayor greeting each other. When he sees Stephanie is strong enough to carry her own suitcases inside, Robbie becomes concerned that the laziness of his ideal town may be in danger. Stephanie is quite taken by her uncle's house, except for a strange smell, which turns out to be a burning cake that her uncle was baking for Miss Busybody. Stephanie is shown to her room, but when, contrary to her uncle's expectations, she wants to play, he hands her a deck of playing cards. Although Stephanie builds quite a proficient house of cards, she seems unhappy somehow. As her uncle comes to check on her, his cake appears to be done. Stephanie seems to like it. As she proposes to go outside to find some kids to play with, her uncle laughs at the silly notion and tells her nobody plays outside. "What if you got tired?"
After a while though, Stephanie finds out her uncle wasn't exaggerating, meeting Ziggy by the ice cream stand, who introduces himself as liking candy. After a handshake, Stephanie can only concur since their hands stick together. And Ziggy confirms kids don't play in LazyTown. As Robbie sees them with his periscope, he is shocked. Ziggy explains the kids just play video games and eat candy at Pixel's house. After realizing Ziggy is only interested in candy, Robbie feels relieved.
Ziggy takes Stephanie to see the other kids who are still in Pixel's house. At first, Pixel and the others aren't the least bit interested in what Ziggy has to say until he sees Stephanie, at which point he no longer minds losing in his video game. Stephanie proposes to play soccer and with her enthusiasm finally convinces the other kids to come outside where they sing the song "Have You Never", led by Stephanie.
When Trixie kicks the ball over a fence, Robbie Rotten approaches and bribes the kids to leave Stephanie alone. Sad, Stephanie sings a reprise of the earlier song, "Have You Never". She makes her way back to her uncle's house and tells her diary about her experience.
Her uncle enters and asks her what's wrong. Stephanie explains the town is a little bit messy. He promises to clean it up, but then the real problem comes to light: the kids do not play outside. Her uncle remembers there being a hero from "an island in the North Sea", with "a big Number 9 on his chest". He explains that they used to send messages to his airship by means of a tube by the mailbox, and finds his old message capsule for her to use. Filled with fresh courage, Stephanie writes a letter to this unknown superhero. She takes it to the mailbox and sees that the tube in question has been blocked with a giant cork and is covered by overgrown weeds. As she attempts to uncover the tube, she catches the attention of a passing Robbie Rotten. To Robbie's horror, Stephanie finally manages to load her uncle's capsule into the tube and pulls the handle, and up flies the message towards the airship seen earlier.
The capsule enters the airship and its message is read by the mysterious man in blue.
The man in blue looks up LazyTown in his book, "History of LazyTown: 1703-1903", in which it is written that LazyTown used to be "a great place to live". He quickly writes back that "help is on the way", delivering his reply by folding it into a paper plane and launching it using a bowling ball, after which he immediately starts engaging the various mechanisms in his airship and jumps into the cockpit to fly it to LazyTown. When he arrives, shortly after his message, Stephanie asks the man in blue if he is "Number 9", to which he points to the number on his back and replies that he is "Number 10". Robbie is shocked that there is "another one". Stephanie asks "Number 10" if he really is a superhero as her uncle described, to which he modestly replies that he is a "slightly-above-average-hero".
Meanwhile, in the playground, Trixie has stranded Stingy on the high end of the seesaw and is about to let go and let him fall. "Number 10"'s crystal begins to glow, warning him that someone is in danger. He quickly flips over to the seesaw, uses it to launch Stingy into the air, catches him and safely places him back on his feet. The hero then returns to Stephanie, only for his crystal to immediately start flashing again. It appears that Trixie is now standing on Ziggy's shoulders, apparently trying to see over the wall and get a glimpse of the new guy, and she is about to fall. "Number 10" flips over to them just in time to catch Trixie.
After witnessing all the commotion, Robbie pledges that these people will not "ruin" LazyTown for him. He digs a trapping pit intended to catch the hero, but catches Miss Busybody instead. Stephanie quickly comes to the rescue with a life-preserver and the Mayor with the cake he baked. Using the rope of the life-preserver and a branch as a pulley, Stephanie and the Mayor attempt to pull Miss Busybody out of the hole, but as they do, the rope begins to break. "Number 10" jumps in just in time to save Miss Busybody and the Mayor who almost fell on his own cake. The Mayor offers an official thank you to "Number 10", who announces that he would prefer to be known as Sportacus. Stephanie declares that LazyTown is really starting to feel like home, to which Sportacus agrees and declares that he will stay, much to Robbie's dismay. Together they get to work on cleaning up the town while Stephanie sings "Bing Bang".
Robbie returns home but falls into his own trap as Sportacus gets back into his ship. Robbie, wrapped up in bandages, finally declares he will stop the "costumed Sporta-loony and [the] pink cheerleader", but he is not in a position to do anything about it for now.