Gloucester coach Dean Ryan, who only snapped up Dave Young and Adam Eustace on Tuesday, is delighted with the capture of Somerville, who can play at loose-head or tight-head.
"Once we appreciated his interest we were thrilled to sign him," Ryan told the official club website.
"To have represented the All Blacks in more than 50 Test matches and be versatile, to operate on either side of the scrum, means he is an outstanding acquisition for us at this stage of his career."
Somerville added: "I have achieved virtually everything possible in New Zealand rugby and to have represented the All Blacks will always be something very special to me.
"This opportunity has developed and the chance to experience a new culture, for myself and my family, and to contribute to a side that is already right at the top of the English Premiership, was exciting to take up.
"I am looking forward to contributing to the side and proving myself in different conditions and against different opponents."



