The UCI Cyclo-cross World Championships are the world championships for cyclo-cross organised by the Union Cycliste Internationale (UCI). Starting in 2020, six events are organized each year – men's elite, women's elite, men's under 23, women's under 23, men's under 18, and women's under 18. Traditionally, the elite events are held on a Sunday with the other events held on the Saturday the day before.

Cyclo-cross is a form of bicycle racing. Races typically take place in the autumn and winter, and consist of many laps of a short course featuring pavement, wooded trails, grass, steep hills and obstacles requiring the rider to quickly dismount, carry the bike while navigating the obstruction and remount. Races for senior categories are generally between 40 minutes and an hour long, with the distance varying depending on the ground conditions. The sport is strongest in the traditional road cycling countries such as Belgium, France and the Netherlands.