Born and raised from a military family with American roots, Brawner graduated from Philippine Military Academy (PMA) "Makatao" Class of 1989, and has been primarily deployed in special operations and infantry units, such as the 2nd Special Forces Battalion and the 103rd Infantry Brigade. Brawner was also known for his role as spokesperson and deputy commander of Task Force Ranao during the Siege of Marawi and for his campaign against hazing during his term as Commandant of Cadets in the PMA. Brawner was also appointed as the first Deputy Chief of Staff for Financial Management, J10, before being named as the commander of the 4th Infantry Division.[4][5]
As a junior officer, Brawner participated in military operations against the communist insurgents and Muslim separatists and terrorists in the Philippines. Throughout his career, Brawner served primarily in both infantry and special operations, before being placed in staff positions. Brawner was named Company Commander of the 6th Special Forces Company was named as Battalion Commander of the 2nd Special Forces Battalion, before being an Operations Officer under the Special Forces Regiment (Airborne). Brawner also served as the Chief of Staff of the 6th Infantry Division, and was also named Chief of Public Affairs of the AFP, before serving as the AFP Spokesperson. Brawner eventually became commander of the Civil-Military Operations Regiment of the Philippine Army.[12][4]
During the Siege of Marawi in 2017, Brawner subsequently served as spokesperson and deputy commander of Task Force Ranao, and served as one of the key commanders during the 5-month long battle.[13][14] Brawner would be later conferred a Commendation Medal and Ribbon for his role.[15] The following year, in 2018, Brawner took command of the 103rd Infantry Brigade under the 1st Infantry Division, and was tasked to root out the remnants of the Islamic State-associated militant terrorist organization Maute Group and its allies within Western Mindanao, including the death of Owayda Marohombsar, also known as Abu Dar, and was the successor of Isnilon Hapilon as the head of the Islamic State-linked terrorists, and the last remaining leader who escaped the Battle of Marawi and was neutralized after follow-up operations.[16][17][18] Due to his accomplishment, Brawner was awarded the Order of Lapu-Lapu by President Rodrigo Duterte.[12] Brawner was also tasked to monitor the 2019 Bangsamoro autonomy plebiscite elections and also led efforts for the Rehabilitation of Marawi.[4] In the aftermath of the Death of Darwin Dormitorio due to hazing, Brawner was named the acting-Commandant of Cadets of the Philippine Military Academy in 2019, along with Rear Admiral Allan Ferdinand Cusi as its superintendent officer-in-charge, following the resignation of their predecessors, then-Brigadier General Bartolome Vicente Bacarro as Commandant of Cadets, and Lieutenant General Ronnie Evangelista as PMA Superintendent due to command responsibility. Brawner later served his term in full capacity as Commandant of Cadets.[19]
In December 2020, Brawner was named as the first Deputy Chief of Staff for Financial Management, J10 after its foundation on 5 November 2020, which is in charge of the AFP's financial control, budgeting, and fiscal management, upon the approval of the Chief of Staff of the Armed Forces of the Philippines.[9] On July 1, 2021, Brawner was named commander of the 4th Infantry Division, in charge with counterinsurgency operations in Northern Mindanao and Caraga regions. During his tenure as division commander of the 4th Infantry Division, Brawner finalized and oversaw a military operation under his supervision that led to the death of communist insurgent leader Jorge Madlos on October 31, 2021, in the outskirts of Impasugong, Bukidnon. Madlos, commonly known as Ka Oris, was the spokesperson of the New People's Army National Operational Command and the National Democratic Front.[13]
Brawner was appointed the 64th Commanding General of the Philippine Army (CGPA) by President Rodrigo Duterte on December 7, 2021, and was eventually promoted to the rank of Lieutenant General on 27 December 2021.[13][12] During his term as the CGPA, Brawner initiated reforms under his leadership thrust, known as "SERVE" thrust, which stands for Soldier, Enhance, Resources, Victorious and Elections, and is aimed at strengthening the soldier's well-being and mental health, enhancement and modernization, resource management, attaining victory against the CPP-NPA-NDF, and securing the country amidst the 2022 Philippine general elections.[20] Then-Lieutenant General Brawner also supervised operations against the CPP-NPA-NDF, the Abu Sayyaf and other connected Islamist groups, and various private armed groups.[21] Brawner also spearheaded the modernization of the Army through the procurement of various weapons and equipment such as the ATMOS 2000 self propelled howitzers, the Sabrah light tank, and various UAVs amongst other weapons, equipment and vehicles. Brawner also launched initiatives aimed at enhancing the personnel's mental health, and expanded benefits of Citizen Armed Force Geographical Units (CAFGU).[22][23]
On July 21, 2023, Brawner was appointed as the 60th Chief of Staff of the Armed Forces of the Philippines, and replaced General Andres Centino, who was named as the Presidential Adviser on the West Philippine Sea.[4] During his assumption speech, Brawner emphasized his command thrust to the acronym "UNITY", similar to the command thrust made by Lieutenant General Bartolome Vicente Bacarro. UNITY stand for Unification, Normalization, Internal Security Operations, Territorial Defense, and Youth, which is aimed at strengthening a unified organization, the normalization process of the Bangsamoro Region, intensified operations against insurgency and terrorism, preparedness against external threats, and youth development, including the potential revival of the Reserve Officers' Training Corps.[24] In October 2023, Brawner laid out plans to upgrade the AFP Cyber Group to a command-style organization named the AFP Cyber Command, which is aimed to expand the AFP Cyber Group's cybersecurity operations and further defend the AFP's cyber networks by enlisting more personnel and procuring additional equipment for cyber defense.[25] Brawner also emphasized the Cyber Group's importance in the modern battlefield due to the rise of both technological threats and cyber soldiers, and is also looking on the Digital and Intelligence Service of the Singapore Armed Forces as a potential model for the expansion of the Cyber Group.[26]
In August 2024, Brawner Jr., became a Philippine Navyspecial forces 'Seal' honorary member after training at the Naval Special Operations Command for SEAL Qualification.[27] In September 2024, Brawner expressed his desire to continually sustain the deployment of the US-made Typhon missile launcher in the country, citing the system's capabilities for external defense operations.[28] Brawner also mentioned in August 2024 the AFP's plans to procure the Typhon missile system.[29]