Williamson has been in brilliant form in the ongoing series and he almost took the Kiwis over the line in the third T20I after playing a knock of 95 runs.
It was possible only after Rohit Sharma hit two sixes in the last two balls to win the match for India.
India are leading the five-match series 2-0 after winning the first two games. India skipper Virat Kohli trusted the winning combination and did not make any change in the playing eleven.
Kumar Sangakkara, the president of the Marylebone Cricket Club, one of the creators of the award, said New Zealand are worthy winners of the award.
England scripted history on July 14 by claiming their first-ever World Cup title. The finals will be remembered for ages as it did not have a winner after the 50-over and super over action both ended in a tie.
The 30-year-old Smith has so far scored 378 runs in the ongoing Ashes series between England and Australia. But Kohli will get a chance to better his lead as India gear up to face West Indies in the two-match series.
For Ben Stokes, his brilliant knock of 84 not out in the final and winning World Cup would remain as a moment of redemption. But his name would also be associated with controversies
Stokes is also likely to receive knighthood after showcasing a match-winning performance in the final as both candidates for next UK Prime Minister, Boris Johnson and Jeremy Hunt expressed their desire to give the player 'knighthood'.
The team was selected by former international players and commentators Ian Bishop, Ian Smith and Isa Guha, along with cricket writer Lawrence Booth, while ICC General Manager Cricket, Geoff Allardice, was the fifth member and convener of the committee.
I never thought I would have to answer this. It's pretty hard to swallow when two teams have worked really hard to reach this point. It's what it is, the rules were there at the start, no one thought it would come down to this. It's a pretty hard loss to swallow. The rules are there. It is something you don't consider when you go out to play.