Bennett, capped 19 times for his country, will make the switch from Glasgow Warriors at the end of the current season after signing a contract to play in the Capital until 2020.
The 24-year-old, a winner of a silver medal at last summer’s Olympic Games in Rio, came off the bench on Sunday as the Scots lost 22-16 in their Six Nations clash with France in Paris.
Bennett said: “A key factor in my decision was that there’s a young squad at Edinburgh, who are going in the right direction and I can feel like I can add to that.
“At 24, I think I could be one of the older boys in the Edinburgh backline, which would be a new experience for me, but one that I’m looking forward to next season.
“I’ve also worked with (Edinburgh acting head coach) Duncan Hodge before as part of the Scotland set-up and I like his approach to the game as well, I think he is a very good coach and I’m looking forward to working with him again.
“The club as a whole seems to be heading in the right direction and I’m excited to be joining and contributing to the side’s progression over the next three years.”
Hodge added: “We’re delighted that Mark will be joining the club ahead of next season. It is great to welcome a young, Scottish international to the club.
“He’s a phenomenal player, who has accomplished a lot both at club and international level at the age of just 24, and his experience will be a welcome addition to our backline.
“Having worked with Mark over a number of years, I know he is ambitious and motivated to develop his own game as well as providing leadership to those around him.
“This will be of huge benefit to the squad and we look forward to welcoming him here at Edinburgh.”