Mignone is an Economist and former International Civil Servant. She was a Consultant at the United Nations Convention to Combat Desertification (UNCCD) in the External Relations, Policy and Advocacy (ERPA) Unit on the 3S Initiative and the Global Mechanism (GM) on the FLEUVE Project in 2018 in Germany. In 2008 she was a Trade Analyst and Economist at the Ministry of Trade, Industry, Regional Integration and Employment in The Gambia for a few years. From 2011 she worked at Daimler AG in Germany.
She was on the Netherlands Traineeship Programme at the World Trade Organization (WTO) in Switzerland in 2010. In 2007 she worked as a Coordinator for the Open Air Laboratories network (OPAL) at Imperial College London in the UK. She gained her Masters in Managing Rural Development at Imperial College London and her first degree with Honours in Geography at Brunel University.