Barrett capped another impressive season in the All Blacks number 10 jersey. The 26-year-old finished the Lions series as top points scorer with 41.
Compatriot Richie McCaw is the only player to win the award in successive years which he did in 2009 and 2010.
New Zealand's Ioane, the youngest of the Player of the Year award nominees at 20, is also a part of the shortlist for the Breakthrough Player of the Year award.
England playmaker Farrell, nominated for the second consecutive year, claimed the European Player of the Year award earlier this year after guiding Saracens to a second straight Champions Cup title.
He started the three tests on the British Lions tour of New Zealand, recording 31 points in the drawn series.
Itoje, who won the 2016 Breakthrough Player of the Year award, offered versatility with his solid performances for England and the Lions this year.
Free-scoring fullback Folau recorded 12 tries for the Wallabies in 10 tests, failing to cross the line in only two matches.
Kelly Brazier and Portia Woodman were nominated for the Women's Player of the Year award on the back of New Zealand's World Cup triumph earlier this year.
They were joined by France's Romane Menager and Safi N'Diaye as Les Bleus came away with the bronze medal at the world event.
England winger Lydia Thompson completes the shortlist having scored 12 tries in 10 matches, including two in their World Cup final loss to the Black Ferns.
The awards will be presented in Monte Carlo on Nov. 26.
(Reporting by Hardik Vyas in Bengaluru; Editing by Ken Ferris)
