Ambachew has replaced Demeke Mekonnen, deputy prime minister, whose shortlived stay on the role spans less than six months.
He had replaced the long-serving chairman, Siraj Fegessa, then minister of Defence, now minister of Transport.
Incorporated a decade ago with a 10 billion Br registered capital, the state-owned military-industrial complex has 17 industrial subsidiaries employing over 19,000 people.
For long a subject of public controversy and legislative criticisms, an army General Kinfe Dagnew (Maj. Gen) had run the company. He resigned from his executive position last month.
Among the newly appointed board members include Azeb Mesfin and Asmelash Weldesellasie, a.k.a Abay Nefso.
Azeb is a widow of former Prime Minister Meles Zenawi,
who was purged from the powerful TPLF political bureau in December 2017, while Asmelash serves as a government whip in parliament.