Williamson missed New Zealand’s triumph against England at Edgbaston, which sealed a 1-0 series win, with an elbow injury.
New Zealand include BJ Watling for the final, which starts in Southampton on Friday, after the wicket keeper recovered from a back injury.
“Kane and BJ have certainly benefited from their week of rest and rehabilitation and we expect them to be fit and available for the final,” said New Zealand coach Gary Stead.
“Playing in a world cup final is a really special occasion and I know the guys are looking forward to getting into their work here in Southampton.
“India are a world-class outfit who possess match-winners all through their line-up, so we’re under no illusion about how tough they will be to beat.”
India’s trio of Wriddhiman Saha, Ravindra Jadeja, and Hanuma Vihari have returned to the Test squad for the final after missing the England series earlier this year with injuries.
The debate around who will open the batting appears to be resolved as Rohit Sharma and Shubman Gill are the only regular openers who have made the cut.
India have bolstered their fast-bowling options by including five seamers — Ishant Sharma, Jasprit Bumrah, Mohammed Shami, Umesh Yadav, and Mohammed Siraj.
Jadeja’s return means there is no place for Axar Patel, who made an impressive debut in the series against England, taking 27 wickets. Ravichandran Ashwin is the other spin-bowling option.
Kane Williamson (capt), Tom Blundell, Trent Boult, Devon Conway, Colin de Grandhomme, Matt Henry, Kyle Jamieson, Tom Latham, Henry Nicholls, Ajaz Patel, Tim Southee, Ross Taylor, Neil Wagner, BJ Watling, Will Young
Virat Kohli (capt), Rohit Sharma, Shubman Gill, Cheteshwar Pujara, Ajinkya Rahane, Hanuma Vihari, Rishabh Pant, Wriddhiman Saha, Ravichandran Ashwin, Ravindra Jadeja, Jasprit Bumrah, Ishant Sharma, Mohammed Shami, Umesh Yadav, Mohammed Siraj