Gardner served two terms as governor of Washington State, from 1985 to 1993.
The Democrat launched the Basic Health Care program and later used his long personal battle with Parkinson’s Disease to spearhead the state’s Death With Dignity law.
He died of complications from the disease late Friday at his Tacoma home.
Senator Maria Cantwell released a statement saying Gardner "was a politician with a personal touch (who) knew how to make everyone in a crowded room feel special."
Gardner was 76 years old.