Gayle was initially a substitute captain for the injured Ramnaresh Sarwan
Chris Gayle has been sacked as West Indies captain and replaced by St Lucian all-rounder Darren Sammy.
Jamaican batsman Gayle, 31, had been in charge of the side since 2007.
But with West Indies seventh in the Test rankings table and eighth on the one-day international ladder, the West Indies Cricket Board has made a change.
Sammy, 26, used his Twitter account to say: "Life now presents its biggest challenge and with God at my side, I'll face it with pride and dignity."
The first St Lucian to represent West Indies, he has emerged as one of the fastest improving players in the squad, performing an important role as a steady seam bowler and a batsman able to bat as the situation demands.
Sammy has appeared in eight Tests, 43 one-day internationals and 19 Twenty20 internationals.
I have built strong relationships with many players and I expect to have the full support of the squad
WICB chief executive Dr Ernest Hilaire said: "Chris Gayle, the former captain, led the West Indies during a challenging period and the board thanks him for stepping up then. But it is now time to pass the mantle on as the West Indies rebuilds."
Selection committee chairman Clyde Butts said: "We are at the dawn of a new era in West Indies cricket and we have entrusted the challenging job of captaincy to Darren Sammy because it is believed that he has demonstrated the attributes of a leader of this diverse group of men."
In the same WICB statement, Sammy said: "Being appointed West Indies captain is an honour and distinction which I will treat with the highest regard and dignity.
"I believe my captaincy of the Windward Islands, a young team which I have been moulding into playing consistently competitive cricket, will stand me in good stead as West Indies captain as we work on building a team for the future.
"I have always given my all when I prepare and play for the West Indies and nothing will change now. I know this will be a difficult challenge and I will take the torch from Chris and hold it high as we forge ahead.
The WICB feels Sammy commands the respect of the Windies dressing room
"I have been playing for the West Indies since 2004 and over those six years I have built strong relationships with many players and I expect to have the full support of the squad."
Gayle, one of the game's most aggressive and charismatic batsmen, initially took on the captaincy when Ramnaresh Sarwan suffered to a serious shoulder injury on a tour of England in the summer of 2007.
He won the one-day series in England and also led the team to a surprise win in the first Test in South Africa at the end of the year but a lean period followed before West Indies beat England in a home Test series in 2009.
When England extracted their revenge in the return series that followed a few months later, West Indies were beaten in three days at Lord's and Gayle, a leading advocate of Twenty20 cricket, declared he "would not be so sad" if Test cricket died out.
Sammy's first assignment will be to lead a 15-man squad on
a tour to Sri Lanka next month,
with Australia-born batsman Brendan Nash as his deputy.
The squad includes one new faces in 22-year-old Jamaican fast bowler Andre Russell, who has been given his chance after only 10 first-class appearances.
West Indies squad: Darren Sammy (capt), Brendan Nash (vice-capt), Chris Gayle, Adrian Barath, Carlton Baugh Jr (wkt), Sulieman Benn, Darren Bravo, Dwayne Bravo, Shivnarine Chanderpaul, Nelon Pascal, Kemar Roach, Andre Russell, Shane Shillingford, Devon Smith, Devon Thomas (wkt).