The 29-year-old back row joins from Sale Sharks and is looking forward to his new challenge north of the border and what he can bring to the black and red jersey.
He said: "I'm mainly a number 8 but I can play on the blindside too. I think my physicality will help the club, especially carrying the ball into contact."
Prior to his time with Sale, Fihaki played with New Zealand provincial side North Harbour for over four years in the ITM Cup.
He made his international debut for Tonga against Japan in May 2013, and now has eight Test caps for his country with two tries to his credit.
Through his involvement with previous clubs and his country, Fihaki is familiar with a number of his new team-mates.
"I've played against a few of the squad - Nasi Manu back in New Zealand and Will Helu in the Premiership, though I've also played with him in the Tongan team.
"Of course I've played alongside Fowlesy [Nathan Fowles] at Sale and also with Phil Burleigh in a Chiefs development side.
"The move will be a great adventure for me and my family and I'm looking forward to getting involved."
Edinburgh Rugby Head Coach Alan Solomons said: "We are delighted that Vili has signed for the club.
"He is a big, powerful ball carrier with international experience.
"I have no doubt that he will add huge value to the team and look forward to working with him."
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