From September 1968 to April 1969, Rio held various positions in the Armed Forces of the Philippines Research and Development Center.

[4] After that, he was appointed assistant general manager of Gasifier and Equipment Manufacturing Corporation (GEMCOR), a company under the Ministry of Public Works and Highways.

He was promoted to brigadier general and appointed as Chief of the Armed Forces of the Philippines Communication, Electronics and Information Systems Service (AFPCEISS), from July 1999 to March 2000.

From April to October 2000, he was designated Deputy Chief of Staff for Communications, Electronics and Information Systems, Armed Forces of the Philippines (J11).

[1] Rio was appointed by then-President Gloria Macapagal Arroyo as Commissioner of the National Telecommunications Commission on February 26, 2001, succeeding acting-Commissioner Agustin Bengzon.

Rio was appointed as Undersecretary for Special Concerns of the Department of Information and Communications Technology and was sworn in on September 13, 2016.

On October 10, 2017, following the resignation of Rodolfo Salalima as DICT Secretary, he was appointed officer-in-charge of the department on the instructions of President Duterte.

[10] His term as officer-in-charge of the department ended after former-Senator Gringo Honasan took his oath of office as DICT Secretary on July 1, 2019.