Millmannoch, also once known locally as the 'Mill of Mannoch' or Kilmannoch, is a ruined mill and hamlet in the old Barony of Sundrum, South Ayrshire, Parish of Coylton, Scotland about a mile from Coylton and Drongan. The 'Trysting Tree' of Robert Burns's poem The Soldier's Return stood nearby. A smithy was once located here in addition to the miller's cottage and later, a farm.

Nineteenth-century historian Paterson described it as being "on the south bank, not far from the 'Craigs o'Kyle', and a more lovely spot never inspired a poet's fancy. The Coyl winds round the mill in serpentine form, in a dark, deep, and rather narrow stream, over which the ash and elm throw their gigantic arms, and in summer, with their waving foliage, almost prevent the sun's beams from playing upon its waters. At the bend, where stands the mill, which is driven by water conveyed from a considerable distance above, the stream is spanned by a rustic bridge for foot passengers, beneath which the waters run in a deep channel, peculiarly pleasing to the eye of the angler."

The weir, on the Water of Coyle, was at the Mill o'Shiel and water, having driven the old water wheel, was discharged into the Millmannoch Dam from which a circa one-mile long lade conveyed it to the retaining dam above the mill at Millmannoch. From there the water power was regulated by a sluice to the water wheel or later a turbine.

Millmannoch, Milnmannoch or Kilmanoch (cell of the monk) was in the old barony of Sundrum, in 1373 held by Sir Duncan Wallace, who had also the barony of Dalmellington. Sir Duncan, although married to Eleanor Bruce, Countess of Carrick, had no offspring and his nephew, Sir Allan Cathcart, inherited, bring with him the possession of the barony of Auchincruive. Large portions of these lands were sold off and the remnants were made into one free barony in 1713 under the name of Cathcart, with Millmannoch as the barony mill, holding still a large amount of multures.

In 1758 the Cathcart barony was sold by Charles Shaw of Sauchrie, Lord Cathcart, to James Murray of Broughton. Murray sold the Sundrum part of the barony with the mill and lands of Milnmannoch (sic) and Bankhead to one John Hamilton and it remained with the family for one hundred and fifty five years. The lands of Milnmannoch and Bankhead were held by one John Morton.

Part of the smithy at Millmannoch was still standing in the early 20th century with in front of it a large granite boulder sunk to ground level with a "dog" fixed into it for cart wheel shods, the metal band or ring on a cartwheel.

Mr. John Thom took four leases of Mill Mannoch in his lifetime, each of fifteen years, his second lease being taken in 1792.

A wooden breast wheel with steel gearing was still in use up until 1884 when improvements included a new iron overshot wheel with gearing for one pair of stones. The set proved less than satisfactory, and in 1902 the whole machinery was replaced. The wheel was removed and a Hercules water turbine was installed with a belt drive. It operated at speed of 450 revolutions and if the gate was fully opened moved 600 cubic feet of water per minute through a single pipe of 21 in. diameter. The changes are very apparent in the gable ends and side walls where the enlargements to the mill were built with brick.