Daniel Akaka, the first native Hawaiian to be elected to the United States Senate, died on Friday aged 93.
The state's governor, David Ige, confirmed his death in a statement, ordering the state's flag be lowered to half-mast.
Senator Akaka served in the US Army at the end of the Second World War, before becoming an educator turned Democrat politician in 1976.
He served more than three decades in Washington before retiring in 2013, holding various positions including as chairman as the Senate Committee on Indian Affairs.
Mr Akaka pushed hard for the recognition of Filipino veterans who fought for the United States during the war, when the Philippines was a US territory.
He also repeatedly introduced a bill pushing for a path for native Hawaiians to gain political sovereignty and self-governance.