The powerful lock, who has won five caps for Wales in the last 12 months, will join up with Dean Ryan’s men on a long-term contract from the start of the 2021/22 season.
The 29-year-old joins from English Premiership side Wasps where he has made just under a century of appearances over the past seven seasons.
“I’m very excited by the move,” said Rowlands. “It’s a new chapter for me, having only played my rugby at one club, so I’m looking forward to some new experiences and challenging myself in a new environment.
“It’s a young group at Dragons with some real potential that has already made good strides forward under Dean [Ryan] and the rest of the coaches.”
On his international ambition, the Rugby School-educated forward said: “I think it’s been my best 12 months from a rugby point of view, even if it’s been a bit of a rollercoaster for us all in other aspects of life.
“I’ve been happy with how I’ve been playing for Wasps and I was really honoured to take up the opportunity to play for Wales. I’ve really enjoyed my involvement with that so far.
“I’m excited about coming to play rugby in Wales and ultimately that is to progress and have more involvements with the national team.
“It’s a fantastic environment to be in and you want to be competing against the best players in Wales.
“I’m looking forward to having the opportunity of another Six Nations campaign and trying to improve as a player and compete for spots in that match day 23.”
Dean Ryan, Director of Dragons Rugby, said: “Will is a proven force who has produced consistent and impressive performances for Wasps in the English Premiership over a number of years.
“He’s an athletic and powerful second row who has also shown his ability be making the step up to international level with Wales over the last 12 months.
“We wanted to strengthen our front five and increase our options so we’re delighted to be able to bring Will to Wales and look forward to him making a big impression at Dragons.”
Hammersmith-born Rowlands made his international debut for Wales in February 2020 when he appeared off the bench in the Six Nations clash with France at Principality Stadium.
Rowlands studied business, administration and management at Warwick University before going on to Pembroke College Oxford, where he gained a BA degree in Economics and Management.
During his time at Oxford University, he played in the varsity matches of 2012 and 2013 against Cambridge University and was also a part-time member of the Wasps Academy.