Conway named in Williamson-led New Zealand T20 World Cup squad
Allen has recovered from the back injury that kept him out of the tour of Pakistan. Michael Bracewell, Mark Chapman, James Neesham and Ish Sodhi are the only players who went on that tour who have made New Zealand's squad.
New Zealand coach Gary Stead believes New Zealand have all bases covered.
"We expect the venues in the West Indies to offer quite varied conditions and feel we've selected a squad with the scope to adapt to those conditions," Stead said.
"Matt has worked exceptionally hard on his skills across the phases of a T20 game to come back into selection consideration.
"Rachin has made every post a winner in the past 12 months and it was exciting to see him continue that trajectory over the summer in the T20 format against Australia."
New Zealand squad: Kane Williamson (c), Finn Allen, Trent Boult, Michael Bracewell, Mark Chapman, Devon Conway, Lockie Ferguson, Matt Henry, Daryl Mitchell, Jimmy Neesham, Glenn Phillips, Rachin Ravindra, Mitchell Santner, Ish Sodhi, Tim Southee, Ben Sears (travelling reserve)