Atty. Nathaniel S. Arevalo began his government career in 1991 with the Civil Service Commission. He passed the Bar in 1997 and went into private practice in 2000. He returned to public service in 2000 at IPOPHL and became the Head of the Legal and Policy in the Office of the Director General. In 2003-2004, he was also designated as Head of the International Patent Systems Division of the Bureau of Patents in a concurrent capacity. His experience in adjudication helped the Director General in deciding IP cases many of which were affirmed by the Court of Appeals and the Supreme Court becoming part of jurisprudence. He also worked on the crafting/revisions of implementing rules, regulations and procedures of the Office of the Director General and some bureaus, on subjects that include patents, utility models and industrial designs, PCT Regulations. Furthermore, he also handled legal (including legal representation) and legislative, international engagements and policy issues, and administrative matters. He drafted Executive Orders establishing the National IP Rights Committee (NCIPR) and the IP Research and Training Institute (IPRTI), which were signed by the President as EO Nos. 736 and 737.

In 2010, he was appointed Director IV of the Bureau of Legal Affairs, where he spearheaded modernization initiatives, strategic organizational upgrading, and institutionalization of the Alternative Dispute Resolution (ADR) as a mode of resolving IP cases/disputes. Outside of the bureau, he also managed legal and policy matters and international engagements. He is the Lead PH Negotiator for IP in free trade negotiations including PH-European Free Trade Association (EFTA), the Regional Comprehensive Economic Partnership (RCEP), ASEAN-European Union, PH-European Union, PH-United Arab Emirates CEPA, PH-Canada FTA, etc.

His dedication to public service in the IP sector was recognized with his appointment as IPOPHL Deputy Director General in 2024, where he served as Deputy Director General for Legal, Policy and External Relations. Currently, he is the Acting Director General of the Intellectual Property Office of the Philippines.