Kanjeng Raden Tumenggung Oemarsono (3 May 1940 – 22 May 2022) was an Indonesian civil servant and politician who was the Governor of Lampung from 1998 to 2003. Previously, he was the province's vice governor from 1995 to 1998.

Oemarsono was born to Sastro Prawiro and R. Ng. Siti Maryamin on 3 May 1940 in Sragen, Central Java, where he attended and graduated from elementary school and junior high school in 1954 and 1957, respectively. Afterwards, he moved to Surakarta, and attended a state high school until he graduated in 1960. He then entered the Gadjah Mada University in Yogyakarta, where he earned an undergraduate degree in social and political sciences in 1966.

Oemarsono entered civil service in 1966 and started to work at the Sragen regional government. He became the Head of the Revenue Services of Sragen in 1985. Several months later, the Wonogiri local council elected him as the Regent of Wonogiri. He was reelected for a second term in 1990.

Before Oemarsono became regent, the Wonogiri region was the poorest in Central Java. During Oemarsono's first years, the region experienced a significant increase in per capita income. He also obtained a 690 million rupiah loan from the central government to construct a drinking water system and a $23 million loan from the World Bank for the re-greening of a catchment area near the Gajahmungkur Reservoir.

Oemarsono launched a food diversification program which encouraged the local populace to abandon bread in favor of cassava. He pushed for the cultivation of rice substitutes in the region such as beans, sweet potato, and corn. He also established a nucleus estate and smallholder farm system for cassava in the region, and received assistance from the central government in the form of kernels for corn plantations.

Oemarsono was nominated by the provincial council of Central Java for the post of vice governor after the death of the previous officeholder, Sujamto, in 1994. This was rejected by the Minister of Home Affairs due to problems regarding bureaucratic seniority.

Oemarsono's work in the region did not go unnoticed by the central government, and in 1989 the regency received the Parasamya Purnakarya Nugraha, an award given by the president to the best-performed regions in Indonesia during the first five-year plan. Earlier in July 1987, the monarch of Mangkunegaran granted him the royal title of Kanjeng Raden Tumenggung. As with other regents who received awards from the president during that time, Oemarsono would go on to become governor. Oemarsono ended his second term in 1995, and Tjuk Susilo replaced him.

Oemarsono was installed as the Vice Governor of Lampung for economic affairs on 18 December 1995 under Poedjono Pranyoto. About a year later, Poedjono became the Deputy Speaker of the People's Consultative Assembly, and resigned as governor. Oman Sachroni, the director general for general government and autonomy in the Ministry of Home Affairs, was chosen to temporarily replace Pranyoto and to hold an election for a new governor. Oemarsono won the election by 35 to 43 votes and he was installed to replace Sachroni on 26 January 1998. Despite the apparent initial support for Oemarsono's leadership in the region, his Javanese ethnicity angered a lot of indigenous Lampung residents and led to months of anti-Javanese protests.