She was the youngest surviving daughter of John Churchill, 1st Duke of Marlborough, and his wife, Sarah Jenyns.

They had five children:[2] From 1714 to 1717, the Duchess was a Lady of the Bedchamber to Caroline of Ansbach,[3] then Princess of Wales.

[5] The duchess is obliquely referred to in Delarivier Manley's 1709 satire, The New Atalantis.

[6] One of those who benefited from the duchess's will was Ignatius Sancho, an African slave whom she took on as a butler following her husband's death.

She left him a pension, but, having failed to find an alternative career, he later returned to the service of the Montagu family.