A native of Cotabato,[2] Hermoso served for about three decades in the Armed Forces of the Philippines.

As part of the Philippine Army, he was part of the 6th Infantry Division (6th ID) which fought against the Moro Islamic Liberation Front (MILF) in Mindanao until the signing of the Comprehensive Agreement on the Bangsamoro in 2014 between the national government and the MILF.

[4] He was also involved in peace negotiations with the Rebolusyonaryo Partido Manggagawa ng Pilipinas/Revolutionary Proletarian Army/Alex Boncayao Brigade (RPM-P/RPA/ABB) and the Cordillera People's Liberation Army (CPLA) as part of the government's technical working groups.

[3] President Rodrigo Duterte appointed Heromoso as assistant spokesperson of the Office of the Presidential Adviser on the Peace Process in January 2017.

[6] Hermoso tendered courtesy resignation on February 16, 2022 as per a directive by Ebrahim as part of a wider reorganization of the regional head's cabinet.