The deal is a real coup for Chris Stirling’s side as the Championship strugglers look to kick-start their season.
Umaga was born in Halifax after his father, the explosive Samoa centre, first arrived in the UK to play for the town’s rugby league side.
He has made seven appearances for Wasps having joined from Leicester Tigers’ academy and played his junior rugby with Old Brodleians.
Umaga, the nephew of All Blacks legend Tana, can also operate at inside-centre or full-back and is due to arrive next week in readiness for Carnegie’s next game against Nottingham in the Championship Cup.
The 20-year-old has also spent time in New Zealand where he helped Auckland to the Mitre 10 Cup title and Stirling said: “Jacob is one of the country’s most exciting young players.
“We’re delighted he’ll be joining the Carnegie squad. He is an extremely talented player and one I am sure Carnegie fans will enjoy watching. This signing is another huge boost for the club and a clear indication of our ambitions.
“I’d like to thank Wasps for their help in arranging this loan deal with Jacob.
“I’m sure he’ll make a big impact on the side and I’m looking forward to seeing him represent the club.”
Wasps Academy manager Jon Pendlebury – who used to work for Carnegie – said: “Sending a young player out on loan has to fit the player and then both clubs so we are pleased Jacob has this opportunity before returning back for the Premiership Shield fixtures in December.”