Street Theatre is a form of theatrical presentation and performance in outdoor public spaces without a specific paying audience. These spaces can be anywhere, including shopping centres, car parks, recreational reserves and street corners. They are especially seen in outdoor spaces where there are large numbers of people. The actors who perform street theatre can range from buskers to organised theatre companies or groups that want to experiment with performance spaces, or use it as a chance to promote their mainstream work. Sometimes performers are commissioned, especially for street festivals, children's shows or parades, but most often street theatre performers are unpaid or gather some revenue through the 'dropping of a coin in a hat' by the audience.

The logistics of doing street theatre necessitates simple costuming and props, and most often there is little or no amplification of sound, with actors depending on their natural vocal and physical ability. This issue with sound has meant that physical theatre, including dance, mime and slapstick, is a very popular genre of theatre in an outdoor setting. The performances need to be highy visible, loud and simple to follow in order to attract a crowd.

Street theatre should be distinguished from other more formal outdoor theatrical performances, such as performances of Shakespeare's A Midsummer Night's Dream in a garden, where there is a discrete space set aside (or roped off) and a ticketed paying clientele who come to see the show.

Often street theatre performers have to get a licence or specific permission to perform through local government or state jurisdictions.