Kilmahew castle was built upon the lands granted to the Napiers by Malcolm, the Earl of Lennox around the year 1290.

The castle itself was built sometime in the 16th century by the Napier family, who owned it for 18 generations.

[citation needed] The estate was inherited by George Maxwell of Newark and Tealing (1678–1744) in 1694, when he assumed the name of his maternal grandfather, John Napier of Kilmahew, but having no legitimate children he was the last of the name, although the Napier of Kilmahew coat of arms survives as a quartering of those of Noble of Ardmore, who therefore now represent the family in heraldry.

[1] Following his death the estate was successfully claimed by an illegitimate daughter, Jean Smith, who married David Brydie, and was finally sold to Alexander Sharp in 1820 in repayment of gambling debts.

Some obvious gothic modifications were done during the 19th century by Alexander Sharp, who owned the castle at the time.