Gruesome footage released by local police shows the elderly man with a broken nose, black eye, numerous deep cuts and blood splattered on his shirt, pants and hands.
He had left his home around 7 p.m. to investigate a nearby disturbance when he was attacked. Police believe a weapon was used.
The attack occurred in Cannington, on the southern outskirts of Perth.
Acting Detective Sgt Alexandra Hill said a weapon was used in a “cowardly, disgusting and appalling act”.
“He’s an 84-year-old man who has lived in this suburb for 40 years… and he was brutally assaulted in his front yard,” she told Perth Now.
“These are horrible and horrific injuries this man suffered in the face. ”
The man was found by police before being taken to Royal Perth Hospital by ambulance where he is awaiting intensive care surgery.
He is in critical condition.
Sgt Hill said there appeared to be no motive behind the brutality.
Two white men aged 25 to 35 have been identified as persons of interest by police.
The victim’s vehicle, which was left with broken glass and bloodstains, is used in the police investigation.
There were at least five other reports of damage and disturbance the night of the man’s assault.
Detectives have opened an investigation into the incident and urged anyone in the area or with CCTV or dashcam footage of the assault to come forward.