The attack, about 3.40pm, appeared to be unprovoked, Detective Sergeant Chris Henderson, of Dunedin, said.
"There doesn't seem to be any rhyme or reason to why it occurred."
The 23-year-old woman struggled with the man, who was known to her, before managing to shut and lock the door on him, Det Sgt Henderson said.
The man, who the Otago Daily Times believes is a neighbour, then left the property.
Armed police cordoned off several blocks around the property, while the armed offenders squad was called to the scene, but were stood down after the man was caught walking in Haywood St a short time later.
Twenty minutes after the emergency call, a woman clutching a bloodied towel to her head was escorted to a waiting ambulance.
Another woman and her child were in the house at the time of attack but were not hurt.
A Dunedin Hospital spokesman said last night the woman was in a stable condition in a general ward.
Det Sgt Henderson said a 44-year-old man had been charged with assault and would appear in the Dunedin District Court today.
"There will be further more serious charges laid once inquiries are completed."
The house remained cordoned off last night and a scene guard was in place.
A full examination of the scene would be carried out today.
One resident, spoken to by the Otago Daily Times, said the man had lived in the neighbourhood for years, was quiet and kept to himself.
