Mr. Moseby's job gets taken by the hotel inspector, Ilsa. It is Zack's fault, and he feels guilty, and tries to set things right. Meanwhile, London's dog, Ivana wants a poker party and Maddie is in charge.
Go-Dance USA is at the Tipton and Max and Zack enter the competition. When they get to the finals, Zack hurts himself. Cody, who thinks he is bad at everything, replaces him. Meanwhile, Maddie becomes London's servant.
Jesse McCartney stays at the Tipton. Zack tries to get his personal effects to sell online, while Maddie and London both think they're meant to be with Jesse forever. Cody tries to enter the local science fair with a laser cutting device.
Kurt Martin (Zack and Cody's father) drops in for a visit, and the three cause a lot of trouble. Zack sneaks into Kurt's tour bus because it's more "fun", but unbeknownst to him, Carey is going crazy with fun back home.
Agnes has a crush on Cody, and Cody hates this. Later on, Agnes loves Zack, and the two hatch a plan to settle things. London's dog Ivana and Maddie's dog Scamp fall in love, and London sadly denies it.
A famous critic is coming to the Tipton—in disguise. When Chef Paolo walks out, Mr. Moseby enlists Cody, along with the help of Zack and the other staff, to help cook him a meal. But will the critic give a good review?
When Zack and Cody accidentally knock over a lamp it punches a hole in the wall between suites. They want to see and hear the girls there. Meanwhile, London is attending Our Lady of Perpetual Sorrow with Maddie, and when she sneaks out of detention, things go awry.
Mr. Moseby's miniature brother, Spencer checks into the Tipton with a shocking announcement: his millions are gone. Now he needs Mr. Moseby's help to get back on his feet. Zack and Cody face a similar situation when Zack is hogging a bike that Cody paid for.
When London hosts her party on Maddie's birthday, all bets are off. Zack, loyal to Maddie, attends her party after trying unsuccessfully to find the perfect gift—but what will she say when she finds out he stole Cody's?
Zack owes money to Maynard, the finalist alongside Cody in the local spelling bee, and asks Cody to forfeit to pay his debt. Maddie is doing local charity work with her class, and London keeps showing them up without actually doing any work.
Arwin participates in the Hotel Engineers' Games, but when a competitor, Irv Wheldon is cheating, Zack and Cody step in. Meanwhile, London starts a fashion store and recruits Maddie for her business functions.
When a local park is going to be demolished, Cody writes an essay to the city, but to no avail. Zack discovers that the park may have historical significance, and races against time to get an injunction against the bulldozers. Esteban tries to get citizenship in the United States.
Zack takes a position in the school paper as the anonymous advice columnist, but begins to abuse his position to get Darlene to like him—until she finds out. London can't sleep, and keeps waking everyone up to help her.
Zack drags Cody to the mall when they miss the morning bus, but soon, their mother shows up and they have to avoid her before she finds them. London tries to get rid of her new step-mother, who shows a little too much interest in London.
Zack and Cody have parts in the school play, A Midsummer's Nightmare, but the girls they like each like the wrong person, which turns out to be the perfect emotional fuel for the Shakespearean classic. Luckily, they don't have to put up with London's obsessive feng shui fling back at the Tipton.
After Zack uses Kumiko Mori as his International Day project, he loses her when she goes shopping. Carey, Zack, and Cody must fill in for her performance at the Tipton, where a group of Japanese guests are expecting a fantastic cultural musical. London and Maddie get trapped in a clothes closet.
After Zack and Cody see a scary movie against their mother's permission, Zack begins to have nightmares of zombies attacking him. Meanwhile, London falls for a poor boy, and doesn't want him to think she's a rich snob, so she pretends to be destitute.
When Zack and Cody join Mr. Moseby's scout troop, Zack turns out to be an excellent fisher, and becomes the troop's hero. Cody finds a way to get food from an outdoorsman nearby, but is caught cheating. Their mother, back home, has to give London and Maddie dating advice for the same boy.
When Carey and Cody take ill, Zack has to take care of them both. During her recovery, Carey ends up winning "Employee of the Month" after she is the only one not to annoy Mr. Moseby in hopes of winning.
Zack and Cody set up a kids' club in the Tipton's lounge every Monday night, but after Cody's plans fail, Zack takes charge and things go great—until his ideas go too far. London tries out a set of new cosmetics, and Maddie is happy to help—that is, until she realizes that they're flawed.
Zack and Cody end up on a game show, Risk It All, but when Cody pushes Zack too far, their chance of winning is up in the air. Back at the Tipton, Maddie tries to recover an angry email she sent by accident.
When Zack is beaten sorely by Ella at minigolf, he enlists Mr. Moseby to help him get better. But when he wins next round, he becomes arrogant and insulting to everyone else. London starts a book club, but without reading in mind.
Zack begins to overeat, and Carey makes him quit sugar entirely, and Cody helps Chef Paolo live healthier. Maddie tries to get bigger hips for an upcoming fashion show, and London tries to get in shape.
When Zack and Cody's former basketball teammate, Jamie, who is now in a wheelchair, visits the Tipton, they try to get him enthusiastic about playing again. Maddie tries to make a student film, but none of her actors are quite up to snuff.
Zack and Cody accidentally send an ancient mummy flying out a window. Cody dresses up as a fake mummy while Zack goes to get the real one to replace him. Maddie, however, wants to sneak the real mummy out, but ends up with Cody instead.
After taking an online aptitude test, Zack becomes obsessed with power and fame, and Cody becomes depressed. Maddie saves an ambassador's life, and steals the limelight away from London, who is less-than-impressed.
This season was shot between 2006 and 2007 and had 22 episodes.
When Zack sees that Carey is ready to blindly sign her singing contract for Mr. Moseby, he insists on getting her a few extra benefits. Cody, on the other hand, is stuck in the middle of a battle between London and Nia, who both need his help in science.
Since none of the staff at the Tipton can get along, Mr. Moseby orders a motivational speaker to come in and help out. They get more than they bargained for when Zack and Cody let loose hundreds of bugs in the hotel.
Cody becomes a severe mysophobe, but is saddened when he finds out how many germs there are if he wants to go skating with Tony Hawk. London and Maddie take private fencing lessons, and fight over the instructor.
After Maddie finds a lost phone, she is certain that its owner and her are meant to be together—until she finds out just who owns it. Meanwhile, Zack and Cody argue over who gets to "borrow" their new friend, Travis, to help them score dates.
Zack makes it onto the basketball team, but never gets to play. Cody, on the other hand, forms a cheerleading squad with several cheerleading rejects to face off with the school's "official" squad at Zack's game.