Dr Smith and Will befriend an old miner named Nerim. After a series of earthquakes indicates that the planet is breaking up, Dr Smith tries to convince them that it is merely the effects of mining, and no harm will come to the planet. John informs him that he is wrong and that the Robinson family will be departing within the day. It is a race against time to escape the crumbling planet.

Shortly after leaving their original crash-site planet, Smith spots a familiar star and, in an amazing show of stellar navigational skill, calculates the course to get back to Earth. He extracts a promise from Don and John that they'll return to Earth, or else he'll destroy his navigation data. They agree, but inform the family at dinnertime that they are headed for Alpha Centauri after all, mainly because the Earth is on the other side of the Sun (how do they know that? - do they know the date? And besides, from Alpha Centauri, Earth revolves clockwise, visible all the time). Smith changes course 180 degrees, then clumsily jettisons most of the fuel. They reach a refueling barge, one of several that Alpha Control put out in 1996, top up the tanks, and resume course for Alpha Centauri, not knowing that they've picked up a tailgater who follows them after Smith reverses course to Earth again. The alarm goes off in the night, and they expend a lot of fuel pulling away from the Earth's

Due to Smith's actions the crew has had to land there ship on an alien planet which is run by cyborgs. Meanwhile the crew try to break free for the captors who promise them power and luxury and they have to save there robot who was crippled by a ray gun.

When an alien believes that the Jupiter 2 has fired a missile at them that alien puts the crew in grave danger for there lives.

The Space Family Robinson go through a food crisis when their plant purifier breaks down. Will and Dr Smith discover a travelling show of circus people, and Will is later tricked in to agreeing to join. It's a race against time for the Robinsons to save will, and keep themselves alive.

The Robinsons and Major West are imprisoned in their camp, after being indited to appear before the a trial in court space crimes. As the trial begins, Dr Smith's name begin's to appear and it is not long before it is realised that all of the Robinson's crimes are due to Dr Smith, and he is indited to appear before the court. Will he be found guilty?

Will and Dr Smith discover an old, abandoned Android Machine. When Dr Smith plays with the buttons on the machine, he accidently orders an Android. He thinks he has it for free, and uses her as his personal slave, assuming she has no human emotions. What will he do when the owner, Zumdish, and his guard turn up...demanding payment?

When a troope of Galactic Gladiators arrive on the planet, they challenge Professor Robinson to a duel, which will be aired all of the galaxy. John declines saying he isn't interested in physical combat. Dr Smith takes up the offer when he makes a deal that if he wins, he will be returned to Earth. Unbeknownst to him, if he loses, which is a near-certanty, Earth will be destroyed.

The beginning of the third season finds the Robinsons having to quickly leave the planet they are on, which is a similar plot to the beginning of the second season. Once in space, the robot is swept overboard and has to be rescued. Then the Robinsons find a prison ship filled with cryogenically preserved prisoners. The prisoners have been interred past their normal sentences due to a malfunctioning timepiece on the prison ship. Professor Robinson repairs the timepiece and frees the prisoners. Robby the Robot makes another appearance, threatening Professor Robinson and Major West.

The Jupiter 2 and all aboard are caught in a space 'time-warp'! After everything seems to return to normal, they're shocked to find Earth within their reach and decide to return home. Though they're perplexed that they are unable to contact 'Alpha-Control', they decide to land in the 'good ole USA' ....only to find it's 1947! As usual, Dr. Smith causes issues & even considers staying behind when the Robinsons and West announce plans to leave.

Dr. Smith answers a distress call from an alien space ship. He arrives there using the Space Pod, and discovers that the aliens want him to operate on (actually, repair), their leader. It turns out that the aliens are a race of some sort of robot that survive as long as their leader, who functions as their central control timepiece, is in working order. The Robinsons come to Smith's rescue in the Jupiter II. The leader is repaired by the robot, and the extended space family Robinson leave the alien space ship safely.

In an episode reminiscent of the first season episode "The Challenge", Professor Robinson and the Robot land the Space Pod on a planet, and Professor Robinson kills an attacking monster, only to discover that he has interfered with a contest where a highly intelligent alien who aspires to rule his home planet is being judged on how well he hunts. The alien forces Professor Robinson to take the role of one of the hunted animals in the contest, allowing the Professor one weapon. The weapon has a defect that imperils Professor Robinson, but the Professor outwits the alien and survives the ordeal.

The primitive beings are actually wards of a computer, Protinius, which can confer temporary advanced sentience on the leading man in order to communicate Protinius' will. The episode also features a temporary camaraderie between Don and Smith, a burying of the hatchet, when Don is rescued by Smith from a pit, and then says ""Doctor Smith"" - using the word Doctor for the first time unknown ages. However, their camaraderie dissolves and the characters are back to ""normal"". Not the first time Smith has become selfless and a man of some integrity, but as usual, Smith returns to normal.

Dr. Smith and the Robot are exploring a cave. Smith pushes several buttons on a conspicuous control panel. The buttons activate a cyborg creating device. It up to Will to stop Dr. Smith.

Before leaving their planet, the Robinsons meet a boy alien called J-5. They take him with them to return him to his home planet. They meet a strange ship, which turns out to be an earth ""lighthouse"" for lost ships. Thinking this ship will help them with extra fuel and star charts they celebrate, however when J-5 learns that they don't have enough fuel to take him home, he angrily sets about to destroy them all with a creation of his imagination. J-5 begins a new life at the lighthouse, and the Robinson's leave in the knowledge he will be looked after by the kindly, old lighthousekeeper.

Dr. Smith, Will, and the Robot are accidentally launched in the Space Pod. They land on a planet that is controlled by an alien machine that creates illusions to confuse visitors and drive them away. The Jupiter II lands and rescues them, and the robot destroys the alien machine.