After Indonesia's independence in 1945, Hazairin served as chief justice of the South Tapanuli court. He also served on the Central Indonesian National Committee. In 1946, he was promoted to regent ("residen") of Bengkulu, also becoming the Vice Military Governor of South Sumatra; during his time as regent, he released his own currency to bolster the faltering economy of the region. In 1948, he served as head of the Great Indonesia Party ("Partai Indonesia Raya"), an offshoot of the Indonesian National Party, which he had helped found.