Ergün was born on 6 August 1966, in Istanbul, Turkey.[1] He graduated from the Turkish Military Academy in 1988, specializing in infantry. He subsequently completed his training at the Infantry School in 1989.[2]
From 1989 to 1992, Ergün served as a platoon and company commander in the 66th Mechanized Infantry Brigade. He then commanded a company in the 70th Mechanized Infantry Brigade from 1992 to 1994. Following this, he served at the Military Academy from 1994 to 1995. In 1995, Ergün was deployed as a platoon commander with the Peace Force Battalion stationed at Bosnia-Herzegovina.[1]
After completing his studies at the Military Academy as a staff officer in 1999, he took on the role of deputy chief of logistics staff with the 66th Armored Brigade. In 2000, he was appointed as an instructor at the Military Academy, during which he pursued a master's degree in the United States until 2003.[1]
Between 2003 and 2010, he worked as a planning officer in the Land Forces's Personnel Planning and Management Department, commanded a battalion in the 4th Commando Brigade, and served as a strategy, defense, and army planning officer with the Turkish Military Representative Committee at NATO headquarters in Brussels. From 2004 to 2005, Ergün was part of the Intelligence and Counterintelligence Department of the International Security Assistance Force (ISAF) in Afghanistan.[1]
Ergün was promoted to the rank of infantry staff colonel in 2007. In 2010, he commanded the 49th Infantry Regiment within the 39th Mechanized Infantry Division. In 2012, he was appointed deputy chief of staff for Training, Evaluation, and Regional Coordination of the 3rd Corps. Later that year, he took on the additional role of deputy chief of the Operations Department.[3][4]
Following his promotion to the rank of brigadier general in 2015, he commanded the 4th Commando Brigade. In 2016, Ergün was appointed head of the General Staff Operations Planning Department. In this capacity, he participated as the General Staff representative in a meeting between president Recep Tayyip Erdoğan and U.S. vice president Joe Biden.[4]
In 2018, Ergün was promoted to major general and subsiqently became chief of operations at the General Staff. Two years later, in 2020, he commanded both the 6th Mechanized Infantry Division and the Joint Special Task Force.[1]
In 2021, he was elevated to the rank of lieutenant general and became the commander of the 3rd Corps. He was promoted to the rank of general in August 2024.[4]