[5] Del Rosario's professional military training includes: Scout Ranger Course and Basic Airborne Course where he ranked third out of 103 in 1980; Field Artillery Officer Basic Course at Combat Arms School, TC, PA in 1989 where he topped his class; Field Artillery Officer Advance Course at Fort Sill, Oklahoma, USA in 1991; Pre-Command Course for Battalion Commanders at the CGSS, TRADOC, PA in 1995; Command and General Staff Course in CGSS, TRADOC, PA in 1999; and Counter Terrorism Course at Naval Postgraduate School, California, USA in 2003.

[6][4] In 2009, then Brigadier General del Rosario returned to Davao City as commander of the 1003rd Infantry Brigade and reactivated the recruitment of indigenous peoples into the Citizen Armed Force Geographical Unit (CAFGU) with the aim of diminishing the strength of the Communist rebels operating in the city's Toril, Calinan, Marilog and Paquibato districts.

As SoLCom chief, del Rosario spearheaded the military mission Task Force Kalihim for the search and retrieval for the remains of Interior Secretary Jesse Robredo who died in the 2012 Philippines Piper Seneca crash in Masbate in August 2012.

del Rosario was appointed by President Benigno Aquino III as Administrator of the Office of Civil Defense in February 2013 following his mandatory retirement from the Armed Forces at age 56.

Concurrent to his duties with the OCD, he also held the position of Executive Director of the National Disaster Risk Reduction and Management Council under the Aquino administration.

[10] As OCD and NDRRMC chief, he led the government's emergency and disaster management councils in assisting victims of the 2013 Bohol earthquake, the Zamboanga City crisis and Tropical Storm Lingling.

Del Rosario resigned from his post in April 2014 citing health reasons, but which critics said was due to the government's poor preparations and response in the aftermath of Typhoon Haiyan.

[13] In June 2016, upon assumption of Rodrigo Duterte as president of the country, del Rosario returned to government service as Undersecretary for Civil, Veterans and Retiree Affairs of the Department of National Defense.

[5] Del Rosario then served as Chairman of the Housing and Urban Development Coordinating Council succeeding Leoncio Evasco Jr. in July 2017.