[4] Harjono attended the air force's aviator school in 1996 and a course on flying the F-16 Fighting Falcon fighter jet the next year.

On 3 July 2003, the squadron was detached by the National Air Defence Command in a standoff against the US Navy F-18 Hornets over Bawean Island.

[4] At the end of his tenure as wing commander in 2014, Harjono was selected by president-elect at that time, Joko Widodo, as his aide-de-camp from the air force until 2016.

[3] Afterwards, in October 2016 he was sent to command the Adisumarmo Airbase[4] in Surakarta, Joko Widodo's hometown, making him part of the Solo Gang.

[8] Harjono issued a call for residents nearby to stop flying balloons in order to prevent flight accidents.

[19] In March 2024, as air force chief of staff Fadjar Prasetyo was nearing his retirement age, three names became the main candidates to replace him.

[20] Andyawan, the-then deputy chief of staff of the air force, was not nominated, as he was also nearing his retirement age.

[23][24] Harjono was installed as the new air force chief of staff on 5 April 2024 at the state place by President Joko Widodo.

[25] A handover ceremony from Fadjar to Harjono was held at the Halim Perdanakusumah Airbase on the same day, attended by cabinet and air force officials.

MP Bobby Rizaldi stated that Harjono was the most feasible candidate for the air force chief of staff due to his age and experience with the president.

[23] Meutya Hafid, the chairman of the first commission—handling armed forces—inside the People's Representative Council, expressed her support for Harjono's nomination due to his experience in handling various aerial problems.