The windmill was built in 1816.  It was leased to the Ashby family the following year. The Ashby family were millers producing stoneground wholemeal flour and the mill became known as Ashby’s Mill for the whole of its working life.

During the 1850s, as the sprawling metropolis of London reached Brixton, the cornfields surrounding the mill were replaced by houses. As a result, much of the wind necessary for turning the sails was prevented from reaching the mill. In 1862 the Ashby family decided to move their business to a watermill on the River Wandle. The sails were removed from the windmill and it was used for storage.

The family’s lease on the watermill ran out in 1902. At this point, Joshua Ashby decided to return the milling business to Brixton. He installed another set of millstones in the windmill, first powered by steam and later by gas, so that he could grind flour without wind power.

Joshua John Ashby, the last miller at Ashby’s mill, closed the business in 1934, as industrially produced bread had become the norm. He died a year later, and the mill became derelict.

In 1957, London County Council (LCC) bought the land, the windmill and the associated buildings for £7,845. LCC decided to turn the 2.5 acres of land into a public open space – Windmill Gardens. By the early 1960s the bakery, outbuildings, Mill House and Mill Cottage had all been demolished to make space for the public gardens.

The windmill was restored over four months in 1964. New sails were made from imported pine timber. Much of the wind-driven equipment installed inside the mill was brought from a derelict windmill in Lincolnshire.

The windmill opened to the public at Easter 1968. For several years it was open each weekend during the summer. Lambeth Council took ownership in 1971. But over the next 30 years the windmill fell into a cycle of restoration and refurbishment followed by vandalism and neglect.

In 2002 the windmill was placed on English Heritage’s Buildings at Risk register. The following year, several local residents formed the Friends of Windmill Gardens and started campaigning for the windmill to be restored.

In 2010 the Heritage Lottery Fund awarded a grant to Lambeth Council and the Friends of Windmill Gardens to restore the windmill. Work began in October and took several months to complete. The sails, cap and tower were all restored, and the 1902 millstones were converted to run on electrical power.

The windmill finally reopened to the public with a celebratory parade and festival, attended by up to 2000 people, in May 2011. Volunteers from Friends of Windmill Gardens opened the mill for guided tours at least once a month during the summer, and initiated an education programme for local schoolchildren.

Friends of Windmill Gardens won the Museums and Heritage Award for restoring an industrial building.

The Friends started grinding flour in 2014, training volunteer millers. The flour is sold on open days and also through local retailers.

Brixton Windmill celebrated its bicentenary with a series of special events, including the first Brixton Beer & Bread Festival, an open-air film night, and the first annual Windmill Lecture.

In 2015 the Friends ran a high-profile campaign to build an education centre in Windmill Gardens.  A year later, Lambeth Council approved plans for the construction of an education centre; planning permission was granted in March 2017. In summer 2018 the Friends ran a successful crowdfunding campaign to raise funds to kit out the building.  After several delays, construction work started in December 2018. The Brixton Windmill Centre was finally completed in July 2020 and the Friends signed the lease and moved in.