Hawaii Gov. Neil Abercrombie signed a gay marriage bill into law during an invitation-only ceremony at the Hawaii Convention Center.
It happened Wednesday morning in a theater in the convention hall near Waikiki.
The signing comes the day after the state Senate passed the bill on Tuesday.
The measure will allow thousands of gay couples living in Hawaii and even more tourists to marry in the state starting Dec. 2.
Senators passed the bill 19-4 with two lawmakers excused.
An estimate from a University of Hawaii researcher says gay marriage will boost tourism by $217 million over the next three years.
The measure is the culmination of more than two decades of debate in the state.
President Barack Obama, a Hawaii native, wrote on Twitter, "Hawaii just became the next state to embrace marriage equality. Congratulations to the Aloha State. #LoveIsLove"