In the past decade an increasing number of adolescent girls in Ethiopia have moved from villages and rural towns to Addis Ababa to improve their own lives and those of their families. While girls' migration is in a way a 'normality', with historically girls migrating for domestic work, the dominant discourse in Ethiopia describes the migration of girls mainly in terms of trafficking and exploitation, in particular when they are doing sex work. As a result, adolescent migrant girls are reduced to passive victims. In this paper we analyse the agency of adolescent migrant sex workers in three 'phases' of their migration process, namely in the decision to migrate, in their lives in the city, and in their future aspirations. We argue that the decisions of adolescent girls to migrate to Addis Ababa is a way of asserting their agency in moving forward with life, yet this agency is taking place in highly constrained circumstances which are strongly related to the gendered ideologies that affect their position in the household, their educational opportunities and their labour market perspectives. The paper is based on a qualitative study conducted in Ethiopia in 2014.