He joined the Scarlets in May 2009 and has gone on to become a first team regular.
He could have qualified for Wales under residency rules but opted to play for England, the country of his birth, and has enjoyed a fine first RBS Six Nations.
The powerful number eight moves to Gloucester Rugby on a three year contract and is looking forward to the prospect of playing in the Aviva Premiership.
"It's a great opportunity for me and one that I'm looking forward to immensely. I grew up just down the road so Gloucester is my local team and I can't wait to run out at Kingsholm for the first time.
"Gloucester have some incredible talent in their squad and play a great style of rugby. Bryan Redpath's told me of his plans for next season and beyond and being part of it is an exciting prospect."
Morgan was quick to pay tribute, however, to the Scarlets for helping him to get to this point in his career.
"I wouldn't be where I am today if it weren't for the Scarlets and I'm incredibly grateful to so many people for the help they've given me along the way.
"Having opted to pursue an international career with England, they understood my desire to play in England and have been brilliant in the way they've handled things."
Head Coach Bryan Redpath is delighted to secure Morgan's services.
"Ben joining us is a very significant signing. He's a big ball carrier who also possesses great handling skills. He'll help get us over the gain line and also do his bit in defence.
"He's international quality and still only 23 years old. He still has so much upside and I think he'll be a great addition to our squad."