White Ferns opening batter Suzie Bates was named the women's ODI player of the year.
White Ferns captain Sophie Devine won the women's Twenty20 (T20) international player award for the third successive year, while veteran Ross Taylor was named men's T20 player of the year.
Williamson's recognition followed a spectacular campaign at the 2019 ICC Cricket World Cup, where his 578 runs at an average of 82, including two centuries, culminated in him being named player of the tournament.
