In his student days, Justice Carpio was chairman of the Editorial Board of the Philippine Law Journal of the U.P. College of Law. He was Editor-in-Chief of The Guidon, the school paper of Ateneo de Manila University. He also served as Managing Editor of the Philippine Collegian, the school paper of the University of the Philippines.

Fresh out of law school, Justice Carpio went into private practice until 1992. He was a Professorial Lecturer of the U.P. College of Law from 1983 until 1992 when he was appointed Chief Presidential Legal Counsel, Office of the President of the Philippines. In 1997, he was Executive Director of the ASEAN Business Law program of the U.P. College of Law.

Justice Carpio also held other important government positions before assuming office as Supreme Court Justice. He was a member of the Board of Regents of the University of the Philippines from 1993 to 1998. He was a member of the Technology Transfer Board of the Department of Industry from 1978 to 1979. He served as Special Representative of the Department of Trade for textile negotiations from 1980 to 1981. He also held numerous prestigious posts such as President of the Integrated Bar of the Philippines Pasay-Makati Chapter (1985-1986). He served as Director of the U.P. Law Alumni Association (1984-1989) and Director of the Philippine Bar Association (1989-1990).

For his "distinguished and exemplary service" to the Republic, Justice Carpio was awarded in 1998 the Presidential Medal of Merit by then President Fidel Ramos. In 1991, Justice Carpio received the Outstanding Achievement Award in Law from the Ateneo de Manila Alumni Association. In 2002, he was also the recipient of the Distinguished Alumnus Award from the Ateneo de Davao Alumni Association.

Justice Carpio is the Chairperson of the Committee on Strengthening the Institutional Capacity of the Judiciary and Co-Chairperson of the Oversight Committee on Halls of Justice. He is also Vice-Chairperson of the Committees on Legal Education and Bar Matters; Public Information; Knowledge Sharing and Regional Cooperation. He is a member of the Committees on Legislative-Executive Relations; Management Committee for Judicial Reform Support Project; Zero Backlog Cases; and Senate Electoral Tribunal.