Dynamic midfielder Tuitupou enjoyed a hugely successful junior career where he won world titles as captain for New Zealand at Under-19 and Under-21 level.
He has replicated that success in the senior ranks featuring strongly in two Air New Zealand titles with Auckland and in the Super 14 championship with the Blues.
Tuitupou has also won acclaim on the international stage with his first All Blacks call-up for the clash with England at Dunedin in 2004.
The talented back will arrive at Sixways at the start of November following the completion of the Rugby World Cup and Air New Zealand Cup.
Worcester's Director of Rugby John Brain said: This is clearly an important signing for Worcester. In Sam we have not just signed an explosive 'go forward' player, but one who at a comparatively young age can offer us a wealth of experience playing at the very top level. It's very exciting news for the club."
Tuitupou added: "After giving very careful consideration to my future I have decided to join with Worcester Rugby Club at the conclusion of the Air New Zealand Cup in October.
"I am excited by the prospect for both me and my family and look forward living in Worcester and becoming part of the Worcester Rugby family as well."