Congress veteran Siddharamaiah has sworn in as the Chief Minister of Karnataka for the second term, along with Karnataka Congress president DK Shivakumar as his deputy.
Governor Thaawarchand Gehlot administered the oath of office at Bengaluru's Kanteerava Stadium.
Eight MLAs also took oath on the occasion as ministers.
Siddaramaiah won from the Varuna constituency in the state assembly election while DK Shivakumar from the Kanakapura constituency.
Karnataka has complex caste equations and a history of voting out incumbent governments.
Only three Chief Ministers before Siddaramaiah - S Nijalingappa (1962 and 1967, three terms including 1956); D Devaraj Urs (1972 and 1978), and RK Hegde (1983 and 1985) had two terms as Chief Minister.
Congress bagged 135 seats in the May 10 elections to the 224-member Karnataka Assembly ousting the ruling BJP, which got 66 seats while the Janata Dal (Secular) secured 19 seats in the results declared on May 13.