Manalo earned a Bachelor of Laws degree from the University of the Philippines and a Master of Arts in International Studies and Diplomacy from Long Island University in New York. She was the first woman to pass the Philippine Foreign Service Officers’ Examinations (FSO) in 1959.
Manalo was based in Manila for eighteen years before getting her first foreign assignment. She was the Philippine Permanent Delegate to the UNESCO from 1990 to 1994, and the European Economic Community from 1979 to 1987. She was Chairwoman of the United Nations Commission on the Status of Women from 1983 to 1988. In 1976, she was named Deputy Secretary General of the ASEAN National Secretariat, and a Senior Official of the Asia Pacific Economic Cooperation in 1996.
She was Undersecretary of Foreign Affairs in charge of International Economic Relations from 1997 to 2001. She served as Philippine Ambassador to Sweden (with concurrent accreditation in Norway, Finland, Estonia, Latvia and Lithuania), to France (with concurrent accreditation in Portugal) and to Belgium (with concurrent accreditation in Luxembourg).
Manalo is the Philippine representative and one of only twelve elected experts to the New York-based United Nations Committee monitoring the implementation of the Convention on the Elimination of All Forms of Discrimination Against Women or CEDAW from 1992 to 2002.
Manalo chaired the HLTF (High-Level Task Force) which drafted the new ASEAN charter that carried the Philippine-initiative creating a human rights body.
Manalo is currently the Chair of the European Studies Program in the Ateneo de Manila University while teaching in the Masters Program level of the Political Science Department. She is the Dean of the HZB School of International Relations and Diplomacy in the Philippine Women's University. She is also a lecturer in the School of Multidisciplinary Studies at De La Salle-College of Saint Benilde (DLS-CSB), a district school of De La Salle Philippines. Apart from that, she is a lecturer in Miriam College and the University of Asia and the Pacific on Philippine Foreign Policy for the Master of Arts in Political Economy program, as well as Comparative European Political Economy. She also chairs the UNESCO National Commission of the Philippines, the educational and cultural advocacy group of the United Nations.
Manalo held leadership positions in various national and international civic and professional groups, such as--the National Commission on the Role of Filipino Women from 1975 to 1986, Federación Internacional de Abogadas, the Women’s Lawyers’ Circle of the Philippines, and ZONTA Philippines.