He played a central role in negotiating the Roem–Van Roijen Agreement during the Indonesian National Revolution (1945–1949), which laid the groundwork for the Dutch-Indonesian Round Table Conference wherein the Dutch finally recognized the sovereignty of Indonesia.

Born into a Javanese family, Roem studied law at the Rechts Hogeschool in Batavia (now Jakarta), during which time he had become politically active in the nationalist movement.

Following the proclamation of independence in 1945, Roem joined the newly formed Republican government where he emerged as an able diplomat and became the Republic's principal negotiator with the Dutch.

[5] After attending the admission test of Medical College, and being rejected, he turned to law, entering Rechts Hoogeschool in 1932 and obtaining the degree Meester in de Rechten in 1939.

[9] Roem was a senior figure in the Masyumi Party, which was banned by President Sukarno in 1960 for its support of the PRRI rebellion.

In 1962 he was arrested and jailed without trial in Madiun, together with Sutan Sjahrir, Anuk Agung, the sultan of Pontianak Hamid, and Soedarpo Sastrosatomo.