On 18-22 September 1917, Aleksandras Stulginskis attended the Lithuanian Conference in Vilnius and was elected to the Council of Lithuania (later Council of the State). He was among the signatories of the Declaration of Independence of Lithuania on 16 February 1918, and the head of the Council of the State's Commission for the return of deportees and prisoners.

From 26 December 1918 to 12 March 1919 Aleksandras Stulginskis served as Minister without Portfolio in the 2nd Cabinet of Mykolas Sleževičius; from 12 March 1919 to 12 April 1919 as Deputy Prime Minister, Minister for Internal Affairs and Minister for Food and Public Works in the 3rd Cabinet of Pranas Dovydaitis; and from 12 April 1919 to 7 October 1919 as Minister of Agriculture and National Assets in the 4th Cabinet of Mykolas Sleževičius.


Aleksandras Stulginskis was a Member, Chairman and Acting President of the Constituent Seimas. He was elected President of the Republic of Lithuania by the 1st Seimas (1922), re-elected by the 2nd Seimas (June 1923 to June 1926). From 17 December 1926 through to April 1927 he was the Chairman of the 3rd Seimas.


On 13 June 1941, Aleksandras Stulginskis was arrested by the Soviet authorities and deported to the Krasnoyarsk region in Siberia, Reshyoty labour camp. In 1952 he was sentenced to 25 years of prison.Following the release after 2 years, he worked as stockman in the Komi Autonomous Republic, warden at the Kvitkevoso forestry farm and agronomist at the Pezmag Soviet farm. Aleksandras Stulginskis returned to Lithuania in 1956, and worked as a senior fellow at Vytėnai olericulture research station from 1957 to 1959. He was one of the founders of the Lithuanian Christian Democratic Party, Chairman of the Party Centre Committee, founder and chairman of the Farmers Union.

Aleksandras Stulginskis worked as editor of "Viensėdis" (Steading) and "Ūkininkas" (Farmer); he died on 22 September 1969 in Kaunas.