Police were called to the property in West Main Street, Whitburn, West Lothian at around 3:30pm on December 27 after a 30-year-old man was found dead.
His death is currently being treated as unexplained pending a post mortem examination.
The man’s next of kin have been informed.
Police said that a 49-year-old man has been arrested.
He is expected to appear at Livingston Sheriff Court on Thursday.