The 44-year-old man was arrested on Monday night and charged with two offences following the attack on the bus at Marrickville that a witness recorded on a mobile phone camera.

Police will allege in court that the driver of the metrobus M30 service had dropped off his last passenger on Marrickville Road about 9.40am on Monday before letting a car overtake him.

The gesture appeared to have upset the driver of a Subaru station wagon travelling behind the bus, police said.

"The driver allegedly approached the bus driver's window and verbally abused the [bus] driver," police said.

"It's further alleged he walked back to his Subaru where he retrieved a shovel from the boot before returning to the bus and smashing the windscreen."

The driver then returned to his vehicle and drove away.

The bus driver was not injured, but was shaken by the incident.

Police reviewed CCTV footage from on board the bus, as well as footage supplied by the witness. Police appealed for the driver of the Subaru to contact police.

Police said a 44-year-old man went to Marrickville Police Station about 7.45pm on Monday and spoke to officers.

He was arrested and taken to Newtown Police Station, where he was charged with destroying or damaging property and being armed with intent to commit an indictable offence.

He was granted conditional bail and is due to appear in Newtown Local Court on March 3.