Dirdeiry started his legal career at the banking sector as an in-house legal advisor to Tadamon Islamic Bank, Sudan and the Central Bank of Oman, Muscat. During the Sudan/South Sudan peace negotiations, Dirdeiry served as permanent delegate/ambassador of the Government of Sudan to the IGAD peace talks in Nairobi, Kenya. He continued in that role until the Comprehensive Peace Agreement (CPA) was concluded, ending the longest African civil war. During the six-year interim period that followed (2005-2011), Dirdeiry took active part in implementing the CPA in different capacities including legal adviser to the Ceasefire Political Commission, Rapporteur of the Constitutional Review Commission, Agent of the Sudan Government to the Abyei delimitation arbitration at the Permanent Court of Arbitration, The Hague.

Dirdeiry’s book ‘Boundaries and Secession in Africa: Challenging Uti Possidetis’ was published by Cambridge University Press in December 2015. Aljazeera Centre for Studies, Doha, Qatar, is publishing an Arabic translation in 2017. Beside his law practice, Dirdeiry teaches international human rights law at the University of Khartoum, contributes in community dispute resolution, and writes in local newspapers and law journals.