In the post-World War II Val Melaina neighborhood of Rome, Antonio Ricci (Lamberto Maggiorani) is desperate for work to support his wife Maria (Lianella Carell), his son Bruno (Enzo Staiola) and his small baby. He is offered a job posting advertising bills but tells Maria that he cannot accept because the job requires a bicycle. Maria resolutely strips the bed of her dowry bedsheets‍—‌prized possessions for a poor family‍—‌and takes them to the pawn shop, where they bring enough to redeem Antonio's pawned bicycle.

On his first day of work, Antonio is atop a ladder when a young man (Vittorio Antonucci) snatches the bicycle. Antonio gives chase but is thrown off the trail by the thief's confederates. The police file Antonio's complaint but say that there is little they can do.

Advised that stolen goods often surface at the Piazza Vittorio market, Antonio goes there with several friends and Bruno. They find a bicycle frame that might be Antonio's, but the venders refuse to allow them to examine the serial number. They call over a carabiniere, who orders the venders to allow him to read the serial number. It does not match that of the missing bicycle, but the officer won't allow them to examine it for themselves.

At the Porta Portese market, Antonio and Bruno spot the thief with an old man. The thief eludes them and the old man feigns ignorance. They follow him into a church where he too slips away from them.

In a subsequent encounter with the thief, Antonio pursues him into a brothel, whose denizens eject them. In the street, hostile neighbors gather as Antonio accuses the thief, who conveniently falls into a fit for which the crowd blames Antonio. Bruno fetches a policeman, who searches the thief's apartment without success. The policeman tells Antonio the case is weak‍—‌Antonio has no witnesses and the neighbors are certain to provide the thief with an alibi. Antonio and Bruno leave in despair amid jeers and threats from the crowd.

Their way home takes them by the Stadio Nazionale PNF football stadium. Antonio sees an unattended bicycle near a doorway and after much anguished indecision, instructs Bruno to take the tram to a stop nearby and wait. Antonio circles the unattended bicycle and jumps on it. Instantly the hue and cry is raised and Bruno – who has missed the tram – is stunned to see his father pursued, surrounded and pulled from the bicycle. As Antonio is being muscled toward the police station, the bicycle's owner notices Bruno in tears and, in a moment of compassion, tells the others to release Antonio.

Antonio and Bruno then walk off slowly amid a buffeting crowd. Antonio fights back tears and Bruno takes his hand. The camera watches from behind as they disappear into the crowd.