Police discovered the body of the woman in her early 30s inside the house on Whittington Avenue in Hayes, west London, at about 09:35 BST on Monday.
Hayes murder: Arrest as missing woman found dead
Officers had been called following concerns for the welfare of a missing woman, the Met Police said.
The 26-year-old man, who is believed to have known the victim, was arrested at a west London hospital later that day.
He remains in hospital but police said his condition was not life-threatening.
There have been more than 100 killings in the capital so far this year.
Read more news of London on our site.