Walker has just completed two seasons in Japan and is a hugely significant recruit as head coach Dean Ryan continues to build his squad for next season. With top-class Italian forwards Marco Bortolami and Carlos Nieto already secured, Walker joins Edinburgh scrum-half Rory Lawson as another major three-quarter to be recruited from outside the club.
Walker has also represented the New Zealand Maori team alongside Carlos Spencer and Christian Cullen and told www.gloucesterrugby.co.uk "I have experienced many great things in my rugby career and been involved with some great players but the challenge that awaits me at Gloucester is one of the most exciting I have ever faced.
"It is a great honour to be joining an English club because the Guinness Premiership is one of the most respected competitions in the world.
"Gloucester are a huge club known the world over and I am thrilled to have the chance to contribute to their future success. I was very impressed with the way Dean Ryan sold the vision of the club, his plans for the future and his thirst for success and I want to be a part of it.
"I am just looking forward to the summer when I can come over and meet all the guys."
Ryan already has Ludovic Mercier - the Premiership's leading scorer this season - and youngsters Ryan Lamb and Brad Davies in his ranks, but felt he needed more cover and experience in the crucial number 10 position.
"It was always our intention to try and recruit a number 10 ahead of next season but Willie can also cover full-back and is also a goal-kicker.
"We already have Ludovic, Brad and Ryan but felt we needed a different option at 10 and believe Willie can provide it. He has plenty of experience at a very high level and is the calibre of player we want going forward.
"We have made no secret of the fact we need to strengthen the squad ahead of next season and this signing confirms that."