However, the 31-year-old will now be released early from his contract to make the move north of the border to join RaboDirect PRO12 club Edinburgh Rugby.
Head Coach Richard Hill said: "I would like to take this opportunity to thank Nikki for his efforts during his time with the Warriors and wish him every success in the future.
"Nikki retains strong international aspirations and has been a part of the Scotland set-up during the current Six Nations campaign. His move to Edinburgh should help his ambitions to play for his country once again and he will leave us at the end of the season with our best wishes."
Nikki Walker said: "I would like to thank everyone at Worcester Warriors for giving me the chance to play in the Aviva Premiership. I have enjoyed my time in Worcester but an opportunity has arisen for my family and I to return home to Scotland. This opportunity was too big for us to turn down.
"I wish the Worcester Warriors all the best in achieving their goals in the future and hope that the loyal fans also get what they deserve."