Frances Guy was born on 1 February 1959, the daughter of David and Elizabeth Guy (née Hendry). She was educated at the University of Aberdeen (MA Hons in Political Studies), also taking a diploma at Johns Hopkins University, Bologna and an MA at Carleton University, Ottawa, in International Relations. In 1989 she married Guy Raybaudo (divorcing in 2015), having one son and two daughters.

Guy entered the Foreign and Commonwealth Office in 1985 and her diplomatic career included the following posts: language training, 1987; Second Secretary (Chancery), Khartoum [Sudan], 1988–91; First Secretary, Iraq desk and Finance Department, FCO, 1991–95; Head, Political Section, Bangkok [Thailand], 1995–96; Deputy Head of Mission, Addis Ababa [Ethiopia], 1997–2001; Ambassador to the Yemen, 2001–04; Head, Engaging the Islamic World Group, FCO, 2004–06; Ambassador to Lebanon, 2006–11; Adviser on the Middle East to the Foreign Secretary [William Hague], 2011–12; Representative for UN Women, Iraq, 2012–14; Head, Middle East Region, Christian Aid, 2014–17; Gender Adviser, Regional Bureau for Arab States, United Nations Development Programme (UNDP), 2017–21.