On behalf of the Secretary General of the United Nations, Costa carried out the administrative and managerial responsibilities for the smooth functioning of the biggest UN campus in Europe, resulting in a massive renovation and a large scale expansion.

During his tenure, Costa focused his attention on integrating the activities of the Office into the peace, security and development agenda of the United Nations.

[6] In 2010 Antonio Maria Costa was awarded the Nils Bejerot prize in recognition of his international contribution to drugs policy and practice.

"[7] Citing more potent strains and increased "cannabis-related health damage", Mr. Costa argued that "the harmful characteristics of cannabis are no longer that different from those of other plant-based drugs such as cocaine and heroin.

[10] As director of UNODC Costa has drawn attention to the role of major international banks in assisting organized crime in money laundering.

He has pointed to evidence that during the financial crisis interbank loans were funded by money that originated from organized crime and drug trade, effectively identifying major banks as money-launderers for about $352 billion in proceeds.

Costa is the author of the novel The Checkmate Pendulum (2014), which draws on his experience from the EU Commission, the UN and his tenure at the European Bank of Reconstruction and Development.