Auckland Transport (AT) could not provide the Herald with details about the injury status of the driver but said their condition was not serious.
The driver, who was on the No 70 route from Botany to Britomart, will be off work while they recover from the “awful attack”, AT said.
“Any abuse or attacks towards our bus drivers is absolutely unacceptable. They work hard so Aucklanders can move around their city and they deserve to have a safe workplace."
A social media user who posted about the attack said the driver was “sitting outside the bus with a bleeding head”.
AT is planning to roll out safety screens to 80% of buses over the next two years to protect its drivers, it said.
Other measures AT takes to improve safety include deploying additional security during school holidays and training drivers in de-escalation techniques.
All of its buses are fitted with CCTV, GPS and panic buttons.
The panic buttons record sound so that staff, who are directly connected, can respond and guide emergency services to intervene, AT said.