She previously served as Director of UNDP's Regional Bureau for Latin America and the Caribbean, appointed to the position by United Nations Secretary-General Kofi Annan in December 2005.

Grynspan is a member of the Program for the Support of Women's Leadership and Representation (PROLEAD) of the Inter-American Development Bank (IDB), and she is former vice president of the board of directors of the International Food Policy Research Institute (IFPRI) based in Washington, D.C. Grynspan was unanimously elected Secretary General of the Ibero-American General Secretariat (SEGIB), at a special meeting of the bloc's foreign ministers on 24 February 2014 in Mexico City, in which representatives of all 22 member countries were present.

[7][8] In September 2016, Grynspan was appointed by United Nations Secretary-General Ban Ki-moon to serve as a member of the Lead Group of the Scaling Up Nutrition Movement.

[9] In early 2021, Grynspan was appointed by the G20 to the High-Level Independent Panel (HLIP) on financing the global commons for pandemic preparedness and response, co-chaired by Ngozi Okonjo-Iweala, Tharman Shanmugaratnam and Lawrence Summers.

In 2014 and 2015, Grynspan was recognized as one of the 50 leading intellectuals of Latin America and, in 2017, she received a Forbes Excellence Award[12] and was granted the Grand Cross of the Civil Order of Alfonso X The Wise[13] by the Spanish Government.