The centre/wing previously played for St Helens rugby league club before moving to Premiership outfit London Irish in the summer of 2005.
"Dominic will add both power and pace to our back line at what is a vital time of the season for us," said Warriors' Director of Rugby John Brain.
Feaunati added: "I'm very excited about my move to Worcester and I've already been impressed by what I have seen. I'm confident I can play a big part in helping the team turn the season around at a crucial stage.
"I've always enjoyed playing at Sixways for Irish and can't wait to be involved in my first game for the Warriors and sample that atmosphere again."
Height: 6ft 1in / 1.85m
Weight: 17st 3lbs / 110kg
Born: June 14, 1978