Centre Ben Te'o will leave Leinster for Worcester next summer.
The 28-year-old New Zealander left the South Sydney Rabbitohs for Leinster in June 2014, but has now agreed a lucrative move to the Aviva Premiership.
Worcester are understood to have fought off strong competition for Teo's signature, a statement of intent as the Warriors continue their battle for top-flight stability.
"Ben is a really exciting talent and has proved he is more than capable of transferring his skills from league to union," boss Dean Ryan told warriors.co.uk.
"His experience and power in the centre will add further depth to our midfield and we're looking forward to him joining up with the side."
Te'o is excited to be joining Worcester at a time of progression.
"Warriors are in a very similar stage in their playing and cultural development that I found when I first joined the Rabbitohs," he said. "I look forward to making a similar contribution at Sixways.
"The investment in facilities and infrastructure is impressive and after speaking with Dean Ryan, it is clearly a club which is on the up.
"Everything is in place for Worcester to become a successful club competing in the top tier."