She began modeling while she was a student at the Winchester School of Art. Early in her career, she appeared in photo spreads for Harper's Bazaar and the English, Italian, and French versions of Vogue.
She became known at the beginning of her career for her unique septum piercing.
The granddaughter of the Duke and Duchess of Devonshire, she was born in Oxnam, Scotland. Following their 1999 wedding, she and her husband, photographer David Lasnet, welcomed one son and three daughters. She died suddenly on December 22, 2020.
Fashion journalist and modeling talent recruiter Isabella Blow made Tennant part of "Anglo Saxon Attitudes," a 1993 British Vogue photo shoot that showcased United Kingdom aristocrats.