After passing the bar examinations, he did not go into private practice, but helped his older brother manage the family business.

In 1945, with no prior political experience, Lopez was chosen by President Sergio Osmeña to be mayor of Iloilo City.

Corp. (San Lorenzo), FG Hydro Power Corporation (Pantabangan-Masiway), FG Bukidnon (Agusan mini-hydro), Bauang Private Power Corporation (Bauang), Panay Electric Company (PECO), First Philippine Industrial Corporation (the major fuel distributor of Shell and Chevron Caltex in the country), First Philippine Realty Corp, First Philippine Electric Corp. (First Philec), First Philec Solar Corporation, First Sumiden Circuits, Inc. (FSCI), First Sumiden Realty, Inc, First Philippine Industrial Park.

In 1949, Lopez became vice-president under President Elpidio Quirino and concurrently worked as secretary of agriculture, serving until 1953.

He died on May 26, 1993, a month after his 89th birthday leaving his wife Mariquit Javellana with whom he had six children: Yolanda, Fernando, Jr. (Junjie), Alberto (Albertito), Emmanuele, Benito and Mita.