Incoming Secretary-General of the United Nations, Antonion Guterres, appointed Mohammed as his deputy on Thursday.
UN Secretary General-designate Antonio Guterres has announced the appointment of female officials among his office.
Mohammed, a development expert who is now Nigeria's environment minister, spearheaded adoption of the U.N.'s global goals for 2030 as Secretary-General Ban Ki-moon's special adviser on post-2015 development planning.
"It is expected that the Minister of Environment will be transitioning to her new role in March 2017".
He said he had no doubt that she would continue to make Nigeria proud at the global level.
She recalled her positions of responsibilities over the last three decades and her contributions to the Millennium Development Goals, the Sustainable Development Goals, and recently working for environment protection as part of President Buhari's vision to transform Nigeria.
Ms Viotti, a career diplomat who was Brazil's United Nations ambassador from 2007 to 2011, is now the under-secretary for Asia and the Pacific in her country's Ministry of Foreign Affairs.
Others include the Independent Expert Advisory Group on the Data Revolution for Sustainable Development, and the Global Development Programme of the Bill and Melinda Gates Foundation.
Guterres, a former prime minister of Portugal who led the United Nations refugee agency for 10 years, won election as United Nations chief despite calls from civil society and some member-states for a woman to be chosen for the first time in the organization's 71-year history.
Born in 1961, and educated in Nigeria and the UK, Ms. Mohammed is married with six children.
He said after taking the oath of office on Monday that "gender parity is a must" and "will become a clear priority from top to bottom in the UN".
Guterres was one of 13 candidates vying to succeed Ban, whose second five-year term ends on December 31.