They combined urine with sand and bacteria in a process that allows the bricks to solidify at room temperature.
"It's essentially the same way that coral is made in the ocean," Dyllon Randall, their supervisor at the University of Cape Town, told the BBC.
Regular bricks need to be baked in high-temperature kilns that produce large amounts of carbon dioxide.
The engineering students at the University of Cape Town (UCT) have been harvesting urine from men's toilets.
On average a person typically produces between 200ml and 300ml of urine per urination and a "bio-brick" needs between 25 litres and 30 litres to grow. But most of this urine is also used to produce about 1kg of fertiliser.