Rodney Copperbottom (voiced by Ewan McGregor) is lovingly brought up by his mother and father to believe that he should follow his dreams. Rodney wants to grow up to be an inventor. He plans to travel to Robot City to meet Mr Bigweld (Mel Brooks), who hosts a television program for new inventions and whose gate is ‘never closed to new ideas’. Rodney invents a clever little robot who can do menial tasks very quickly, and he travels to Robot City to show it to Bigweld. He is disappointed when he is not allowed in to see Bigweld. He soon discovers that Bigweld’s enterprise has been taken over by the wicked Ratchet (Greg Kinnear), who is interested only in making money.

Ratchet is driven by his evil mother whose plan is to make all robots upgrade to new bodies rather than repair their old ones. So mother and son destroy all spare parts. Robots found wandering the streets at night are taken to the Chop Shop where they are melted down for scrap metal. Their campaign slogon is ‘Why be you when you can be new’. Rodney sees the wickedness of the plan and starts repairing all the broken robots. He soon becomes the robots’ representative and Ratchet’s number one enemy. Together with his new friend Fender (Robin Williams), Rodney rallies the other robots to overthrow Ratchet’s Industries.