Following her graduation, Cox worked as an adviser to Labour MP Joan Walley, before moving to Brussels to spend two years advising Glenys Kinnock, who was then a Member of the European Parliament. She became an aid worker in developing countries for Oxfam, eventually becoming the charity's head of policy.[when?] Her charity work led to a role advising Sarah Brown (wife of former British Prime Minister Gordon Brown), who was spearheading a campaign to prevent deaths in pregnancy and childbirth.[6][12] She became the national chair of the Labour Women's Network and a senior adviser to the Freedom Fund, an anti-slavery charity.[9][10]