The Constitution of the Democratic Socialist Republic of Sri Lanka has been the constitution of the island nation of Sri Lanka since its original promulgation by the National State Assembly on 7 September 1978. As of October 2022 it has been formally amended 21 times.
It is Sri Lanka's second republican constitution, replacing the Sri Lankan Constitution of 1972, its third constitution since the country gained independence within the British Commonwealth as the Dominion of Ceylon in 1948, and its fourth constitution overall.