Emergency services were called to a report of a man having been found injured within a property on Campbeltown Drive at around 4.15pm on Saturday.
Police said the 48-year-old man was taken to hospital, where he died a short time later.
His death is being treated as unexplained, following a postmortem examination.
However, officers said there are no suspicious circumstances.
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A report will be sent to the procurator fiscal.
Chief Inspector Helen Downie said: “Police received a report of a 48-year-old man having been found injured within a property on Campbeltown Drive in Kilmarnock around 4.15pm on Saturday, 31 January, 2026.
“The man was taken to hospital, where he died a short time later.
“Following a postmortem examination, the death is being treated as unexplained, but there are no suspicious circumstances.
“A report will be submitted to the Procurator Fiscal.”