He worked for decades in the Department of Industry and the Ministry of State Secretariat until his appointment as the Head of the National Land Agency in 1988.

Afterwards, Soni pursued further studies at the Leibniz University Hannover, where he obtained a degree in marine engineering in 1961.

He briefly worked in the presidential office before being appointed by State Secretary Sudharmono as his assistant for administrative affairs in 1981.

[8] After five years heading the National Land Agency, on 19 March 1993 Suharto appointed Soni as the State Minister for Agrarian Affairs.

In January 2006, while he was in Pakistan, Soni was summoned by the attorney general as a witness in a corruption case which involved the misappropriation of the Hilton Hotel at the Gelora Bung Karno Stadium.

Soni returned to Indonesia later that month and stated that he has no knowledge about the case as the misappropriation occurred after he left office.