Born in Newcastle, Australia, Stephanie Williams began her training at the age of 8 at the Marie Walton-Mahon Dance Academy before relocating to Melbourne to complete her training with The Australian Ballet School. In 2005, Williams was awarded the Gold Medal at the 10th Asian Pacific International Ballet Competition in Tokyo before graduating from The Australian Ballet School with Honours and as Dux of her year. Upon her graduation she performed the dual role of Odette/Odile in the traditional Swan Lake. Williams was a 2005 National YoungArts Foundation Winner in Dance.
Williams joined The Australian Ballet in 2007 as a member of the corps de ballet and was promoted to coryphée in 2008. During her time with The Australian Ballet her repertoire included Christopher Wheeldon's After the Rain, Jerome Robbins' Afternoon of a Faun with international guest artist Cedric Ygnace, Idée Fixe in Kryzsztof Pastor's Symphonie Fantastique, Prelude, solo and pas de deux in Les Sylphides, Cigarette solo and pas de deux in Suite en Blanc, Prayer in Coppélia, Lilac Fairy and Earth Fairy in Stanton Welch's The Sleeping Beauty and Nacho Duato's Por Vos Muero.
In 2009, Williams was a guest artist with Christopher Wheeldon's Morphoses, performing principal roles in Commedia and Fools Paradise. Later that year she worked with Wayne McGregor creating a role in his work Dyad 1929 and becoming the youngest ever winner of The Australian Telstra Ballet Dancer of the Year award, as well as the people's choice award.
Starting in August 2011, Williams spent six months with Het Nationale Ballet in Amsterdam before joining ABT as a member of the corps de ballet in January 2012.
Her repertoire with the Company includes a Shade and Lead D'Jampe in La Bayadère, the Fairy Summer in Frederick Ashton's Cinderella, the Mazurka Lady in Coppélia, Zulma in Giselle, one of the Nutcracker's Sisters and the Spanish Dance in Alexei Ratmansky's The Nutcracker, a Carnival Dance in Othello, Lady Capulet and a Harlot in Romeo and Juliet, the Fairy Fleur de farine (Wheat flower) and the Countess in The Sleeping Beauty, the pas de trois and a big swan in Swan Lake and roles in After You, The Brahms-Haydn Variations, Company B, Drink To Me Only With Thine Eyes, Raymonda Divertissements and With a Chance of Rain. She created the Gold Fairy in Alexei Ratmansky's The Sleeping Beauty, a leading role in Her Notes and a role in AfterEffect.