Hope and Powell split Windies white-ball captaincy
Nicholas Pooran, who had captained both white-ball teams, stepped down in November after West Indies' first-round exit from the T20 World Cup in Australia.
The new captains will begin their tenures next month in the limited-overs leg of their South Africa tour, which also features two tests.
Kraigg Brathwaite remains captain of the test side.
"It is a tremendous honour and privilege to be appointed captain of any West Indies team," wicketkeeper-batter Hope said in a CWI statement on Wednesday.
"To lead a team that is of such incredible significance not only to myself and my teammates but to our legion of fans the world over, is something one dreams of as a child."
West Indies lag well behind seventh-placed Afghanistan in the Super League standings and will have to go through qualifiers in Zimbabwe in June-July if they are to make this year's ODI World Cup in India.
West Indies are assured of their place at next year's T20 World Cup as they co-host the tournament with the United States.
"To be asked to carry the flag for the people of the Caribbean, there’s no bigger role in cricket in the region" all-rounder Powell said.
"I'm a passionate cricketer who believes in leading from the front and always giving 100%."