Disney XD's first season of Randy Cunningham: 9th Grade Ninja premiered on September 17, 2012, and finished on February 8, 2014. It contains 52 x 11 minute episodes.
A freshman boy named Randy Cunningham finds a Ninja guidebook and ends up becoming a ninja. With his best buddy Howard Weinerman, the two have to navigate everyday teenage life at high school while taking on monsters and madmen bent on freeing an evil 800 year-old Sorcerer. This sorcerer was imprisoned beneath Norrisville High by the original ninja and guarded ever since by Randy’s predecessors.
Randy and Howard try to get into a cool zone in the bleachers when watching their school play basketball. When one of the triangle-playing band members (Bucky) is fired, The Sorcerer turns him into a ferocious monster.
When Randy discovers that the Norrisville philanthropist, Hannibal McFist, is his enemy, he has a hard time trying to convince Howard that the one they believed to be their hero is actually an evil villain working with The Sorcerer.
The Ninja fights a lizard, which copies a sample of his snot. Later Randy and Howard attend a party Bash is throwing, but it's a scheme so McFist can find the ninja by sampling everyone's snot bombs and matching it to the Ninja.
Randy and Howard take a trip under their school and go through the scary old gym in an effort to find a mythical golden doctor's note that can help them skip gym, but its not as easy as they hoped it would be.
Randy and Howard want to rescue their science project but Randy accidentally brings the class skeleton, and Mrs. Driscoll's "husband", Jerry back to life. The mad scientist also plans revenge on Viceroy.
Randy and Howard form a band to enter the school's Battle of the Bands. Randy has to choose between being the ninja or his friendship with Howard while McFist tries to use a truth device that will reveal the ninja's identity during the show.
After an argument between Randy and Howard, a monster attacks during a routine "monster drill" where Howard is pretending to be the ninja. Randy must find a way to get to his mask back from the school library and to apologize to his friend.
Randy travels to the forest to retrieve a sap from a sacred tree in order to restock his ninja gadgets, but McFist beats him there and snags the tree for his holiday party. Randy poses a Ninja Santa to get in to the party and winds up defending himself against a robot snowman and his team of elves.
After a power outage at school, a Stankified Monster frozen in ice is freed. When Randy de-stanks him, he and Howard learn that his name is Dickie and his monster form was frozen in ice by the Ninja of 1985. When Dickie is saddened by this and how he missed his chance with Tawny , the Sorcerer takes the opportunity to re-stank him and find out what is the object of his stank.
The Wave Slayer relays are occurring in Norrisville as Randy and Howard accidentally wrecks the Wave Slayer where an accident injures Buttermaker and causes Howard to take his place. The Sorcerer takes the opportunity to turn Buttermaker into an aquatic monster that attacks the opposing team.
Randy must learn a valuable new lesson about respect and humility when after accidentally breaking his sword, he enlists the help of S. Ward Smith to get a custom-made sword. Meanwhile, S. Ward Smith's protege, Brent, believes he was replaced by Howard and wreaks havoc on the school when he is changed into a monster by the Sorcerer.
In order to score a limo ride with soccer super star Pitch Kickem, Ninja swipes a pair of shorts to help him win a shoot-out competition. When McFist sends an I.D. Bot to find the shorts, Randy’s identity is compromised and Howard must take Randy’s place in the competition.
During the 50th Anniversary Celebration of McFist Industries, the Ninja outs McFist as a villain to the entire town. But with his cover blown, McFist is finally able to focus all of his power on destroying the Ninja.
Randy becomes so dependent on the Nomicon’s wisdom that he goes to it for advice on everything. To teach him a lesson, the Nomicon traps him inside and puts an alternate consciousness in Randy’s body, forcing Randy to try to find a way out of this mess.