Barry Lawless, 83, was at his home in Mandurah, south of Perth, at about 9pm on Wednesday when an intruder stormed in and attacked him with a makeshift weapon.
The attack occurred when Mr Lawless' young children, including his daughter, 12, and son, 11, who sprang into action and chased the intruder away.
'My boy, trying to chased him out of the living room, he said "I'll get him dad". It was very traumatic, I can tell you,' Mr Lawless told Seven News.
'I had so much blood coming out of me, I could hardly see what I was doing,' an emotional Mr Lawless said.
He added that he did not know his attacker and nothing was stolen from his home.
Mr Lawless believes it was a random attack, and his home was only targeted because he left his door open due to the hot weather.
'I mean you don't think somebody's going to charge into your house like that when you're just sitting there, you know? It's a bad world,' he said.
Mr Lawless underwent surgery on Thursday night after sustaining two breaks to his head and losing one and a half litres of blood.
Police said they were speaking with a 40-year-old man who was assisting them with their investigation.