Greenside High School increased the size of its swimming pool in 2013/14. The main sport field is used for cricket, rugby, touch rugby, soccer, and athletics. Their hockey fields, which run adjacent to Parkview Golf Club, are mainly used for hockey, but have also been used for cricket, soccer and rugby. Greenside has four basketball courts which also double up as netball courts. There are eight tennis courts.
The school competes in RAPS, FEDA, EADS, and (as of 2017) GRADS.[1] In 2013, students launched a production of Fame.
In 2017, students from the Greenside High School robotics team traveled to Costa Rica to take part in the WRO Global Robotics Tournament. Greenside High School was the only public school from South Africa to represent the country in this tournament.[2]