Her BBC series A Very British Murder examined the "morbid national obsession" with murder. The series looked at a number of cases from the 19th century, beginning with the Ratcliff Highway murders which gained national attention in 1811, the Red Barn Murder of 1826 and the "Bermondsey Horror" case of Frederick and Maria Manning in 1849.

Worsley was born in Reading, Berkshire. Her father, Peter Worsley (b. 1939), taught geology at Reading University, while her mother, Enid (née Kay; 1945) is a consultant in educational policy and practice. She has a younger brother, Tom Worsley (b. 1976).

Worsley began her career as an historic house curator at Milton Manor, near Abingdon, in the summer of 1995. From 1996 to 2002, she was an Inspector of Historic Buildings for English Heritage in the East Midlands region. During that time she studied the life of william Cavendish, 1st Duke of Newcastle and wrote the English Heritage guide to his home, Bolsover Castle. In 2001 she was awarded a DPhil degree from the University of Sussex for a thesis on The Architectural Patronage of william Cavendish, first Duke of Newcastle, 1593–1676. The thesis was later developed into Worsley's book Cavalier: A Tale of Chivalry, Passion and Great Houses.

During 2002–2003, she was Major Projects and Research Manager for Glasgow Museums before becoming Chief Curator at Historic Royal Palaces, the independent charity responsible for maintaining the Tower of London, Hampton Court Palace, Kensington Palace State Apartments, the Banqueting House in Whitehall and Kew Palace in Kew Gardens. She oversaw the £12 million refurbishment of the Kensington Palace state apartments and gardens.

In 2005 she was elected a Senior Research Fellow at the Institute of Historical Research, University of London; she was also appointed visiting professor at Kingston University.

Worsley lives in Southwark by the River Thames in south London with her husband, the Architect Mark Hines, whom she married in November 2011. With reference to having children, Worsley says she has been "educated out of normal reproductive function". She later said her statement had been "misinterpreted and sounded darker than I'd intended."

In 2012 she co-presented the three-part television series Antiques Uncovered, with antiques and collectibles expert Mark Hill, and (broadcast at the same time) Harlots, Housewives and Heroines, a three-part series on the lives of women after the Civil War and the Restoration of Charles II. Later that year she presented a documentary on Dorothy Hartley's Food in England as part of the BBC Four "Food and Drink" strand.

In 2014, BBC Books published her book, A Very British Murder, which was based on the series. In April 2016, Worsley published her debut children's novel, Eliza Rose, about a young noble girl in a Tudor Court. In 2017, Worsley published a biography of Jane Austen titled Jane Austen at Home: A Biography.

In July 2015, she was made an honorary Doctor of Letters by the University of Sussex (where she completed her doctorate).

In 2016, Worsley presented the three-part documentary Empire of the Tsars: Romanov Russia with Lucy Worsley in January and Lucy Worsley: Mozart's London Odyssey in June. In September 2016, she was filming an upcoming series A Very British History for BBC Four. In December she presented and appeared in dramatized accounts of the three-part BBC series Six Wives with Lucy Worsley. In 2017 she presented a three-part series entitled British History's Biggest Fibs with Lucy Worsley, debunking historical views of the Wars of the Roses, the Glorious Revolution and the British occupation of India.