Root led England in a record 64 Tests but his role became untenable after they managed one win in their last 17 Tests, a run which included a 4-0 Ashes thrashing in Australia and a 1-0 series defeat in West Indies.
"I had no hesitation in offering the role of Test captain to Ben," Rob Key said in a statement in his first major appointment since taking over as the managing director of England men's cricket earlier this month.
"He epitomises the mentality and approach we want to take this team forward into the next era of red-ball cricket."
Root, who initially wanted to continue in the job, stepped down citing the heavy toll it took on him.
The 30-year-old Stokes, who has scored more than 5,000 runs and taken 174 wickets in his 79 Tests for England, called it an "honour" to lead the Test side.
"This is a real privilege, and I'm excited about getting started this summer," the Durham player said.
Arguably the greatest all-rounder of his era, Stokes acknowledged Root's role in his development as a leading figure in the England dressing room.
"I want to thank Joe for everything he has done for English cricket and for always being a great ambassador for the sport all across the world," Stokes said of England's batting mainstay.
"He has been a massive part of my development as a leader in the dressing room, and he will continue to be a key ally for me in this role."
OBVIOUS CHOICE
While Stokes was an obvious choice to replace Root, his battles with injuries and workload remain a concern for the team.
He also took an indefinite break from cricket last year to focus on his mental health.
England and Wales Cricket Board (ECB) chief executive Tom Harrison was optimistic of a glorious "new era" under Stokes.
"He cares deeply and passionately about what it means to represent England and he will lead us into a new era with great pride," Harrison said.
"It's an important summer for our Test side and Ben will, I am sure, relish the challenge before him and his team."
Stokes' first assignment will be a two-match home series against New Zealand in June.
As Test captain, his views will be crucial to the future of James Anderson and Stuart Broad, England's two most prolific Test bowlers, who have been left out of the squad recently.
Under Key, England have also advertised for separate red-ball and white-ball coaches following Chris Silverwood's resignation in February.
Cricket - Third Test - West Indies v England - National Cricket Stadium, St George's, Grenada - Mar 25, 2022 England's Ben Stokes in action Action Images. Reuters/Jason Cairnduff
