Family members found the 54-year-old man seriously injured at his home in Craigie Avenue around 5.30pm on Sunday.
He was taken to University Hospital Ayr where medical staff describe his condition as critical but stable.
Police said it is not clear how the victim came to be injured and are trying to piece together his movements.
They are treating the incident as attempted murder and appealed for information.
Detective Sergeant Barry Walker said: “The victim was found seriously injured within his home and it is vital that we establish what happened to him and identify the person or persons responsible for this serious crime.
“I would appeal to anyone who was in the area of Craigie Avenue over the weekend and may have heard a disturbance, or noticed anyone behaving suspiciously, to please get in touch.
“Anyone with information is asked to contact Ayr CID via 101, quoting incident number 3231 of Sunday 12 August 2018. Alternatively you can call CRIMESTOPPERS on 0800 555 111 where details can be given in confidence.”