Sarah was born Sarah Elisabeth Bowser on 26 March 1962. She is the younger of her parents' two daughters. Motivated by her Christian faith she decided to follow a career in nursing after taking her A-levels.
She began her nursing career in 1980 undertaking a nursing degree at South Bank Polytechnic, with clinical placements at St Thomas' Hospital.
In 1987, she married Eamonn Mullally. Together, they have two children; a daughter and son.
She then held clinical nursing posts at St Thomas' Hospital and The Royal Marsden Hospital and then moved into nursing leadership roles, firstly at the former Westminster Hospital (where she was a ward sister and head of practice development) and then as director of nursing at the Chelsea and Westminster later becoming deputy and acting chief executive officer. In 1999 she was appointed as Chief Nursing Officer and director of patient experience for England. She was 37 and was the youngest person to hold these positions.
Sarah started training for ordained ministry in 1998. She was ordained in the Church of England as a deacon in 2001 and as a priest in 2002. From 2001 to 2004, she served her curacy as a part-time minister at the Parish of Battersea Fields in the Diocese of Southwark.
In 2004, Sarah left her position as Chief Nursing Officer to pursue full-time ministry. She then served as an assistant curate at St Saviour's Church, Battersea Fields from 2004 to 2006.
In the 2005 New Year Honours, Sarah was appointed a Dame Commander of the Order of the British Empire (DBE) in recognition for her contribution to nursing and midwifery.
In 2006, she became the team rector of Sutton team ministry at St Nicholas' Church in Sutton, London.
From 2012 to 2015, she was the canon treasurer at Salisbury Cathedral in the Diocese of Salisbury.
In July 2015, she was consecrated a bishop by Justin Welby the Archbishop of Canterbury, during a ceremony at Canterbury Cathedral. She was installed as Bishop of Crediton, a suffragan bishop in the Diocese of Exeter.
In September 2015, she became the first woman in the Church of England to lead an ordination service, ordaining two deacons, as priests.
The Rt Revd and Rt Hon Dame Sarah Mullally DBE was installed as the 133rd Bishop of London at St Paul's Cathedral on 12th May 2018. She now sits in the House of Lords as one of the Lords Spirituals. She was sworn in as a member of the Privy Council on 14th March 2018.