After finishing his high school education, he moved to Lima, enrolling in the Federico Villarreal National University, graduating with a law degree.

[1] In Lima, he resided in the San Miguel District, where he continued as a member of the Juventud Aprista Peruana, serving as Secretary of International Affairs of the youth wing from May 1983 to August 1985.

[1] At government level, Rosas was appointed to the Ministry of Agriculture in the second presidency of Alan García, in the position of General Manager of the National Institute of Natural Resources (INRENA), serving from September 2006 to January 2008.

After a brief stint at the Ministry, he was appointed Director of the National Fund for Social Development Cooperation (FONCODES) in May 2008,[2] serving through August 2008, being replaced by fellow party member, Carlos Arana.

[5][1] At the 2016 general election, Rosas was selected to run for Congress with the Popular Alliance congressional list, which included in the coalition the Peruvian Aprista Party.