She has held several senior portfolios in the United Nations, most recently serving as the Deputy Special Representative (DSRSG) for the Office for West Africa and the Sahel during 12 February 2016 to 6 August 2017.

[8] Upon completing her studies in Paris, Guebre Sellassie returned to Addis Abbaba, where she had a distinguished career practicing law and held positions at the Ministry of Foreign Affairs within the Ethiopian government.

[11] In 2007, Guebre Sellassie was appointed Director of the Political Affairs Division and Head of the Goma Regional Office for the United Nations Mission in the Democratic Republic of Congo (MONUC), renamed United Nations Organization Stabilization Mission in the Democratic Republic of the Congo (MONUC) in 2010.

[12] Following the Kiwanja Massacre in November 2008, Guebre Sellassie and Gen. Bipin Rawat, the recently-appointed military head of the UN peacekeeping force in North Kivu, brought their commands together for evaluation.

"[13] Reforms included the creation of joint protection teams comprising military and police personnel and civil affairs, human rights, and child protection staff operating from the UN's forward bases; a mobile-phone based early warning system, in which community members were provided with devices to alert peacekeepers of unrest; community alert networks that allowed for bases to be contacted around the clock; Community Liaison Assistants (CLAs), an expanded role for Congolese translators to also act as community monitors and information gatherers; an emphasis on civilian outreach; increased foot patrols, including escorting women to their homes and workplaces and issuing security advisories in high-risk areas; and deployment of 30–35 troop standing combat units to areas deemed vulnerable.