Elected to the Philippine Senate from 1957 to 1963, he was the first Filipino film actor to parlay his fame into a substantial political career, paving the way for other future Filipino entertainers-turned-politicians such as Senators Ramon Revilla Sr., Tito Sotto, Ramon "Bong" Revilla Jr., Jinggoy Estrada, Lito Lapid, Freddie Webb, Robin Padilla, and President Joseph Estrada.

[8] When the Philippine film industry was held to a standstill during the Japanese occupation from 1941 to 1945, de la Rosa remained in the public eye as a bodabil performer at the Life Theater in Manila.

[6][10] In the 1957 general elections, de la Rosa ran and won a seat in the Philippine Senate under the banner of the Liberal Party.

As a Senator, he was active in issues of particular concern within his home province of Pampanga such as fisheries and agriculture, emerging as a strong advocate for nationalization of those industries.

[11] Appropriately, de la Rosa was also interested in issues relating to the Filipino film industry, co-authoring a bill that would lead to the establishment of a Board of Censors.

His residual popularity as a film star, as well as the unpopularity of incumbent re-electionist Nacionalista Carlos P. Garcia made him a credible candidate.

[14] During the administration of Ferdinand Marcos, de la Rosa was also named as Philippine Ambassador to the Netherlands, and to the Soviet bloc countries of Poland, Bulgaria and Czechoslovakia.

[14] After retiring from the diplomatic corps, De la Rosa made his last foray into politics by unsuccessfully running in the 1984 Batasang Pambansa parliamentary election.

Shortly before his death from a heart attack in 1986, he played one last acting role, in a guest spot on the popular drama anthology Coney Reyes on Camera.