The 25-year-old will join up with Richard Cockerill’s side in the summer after five seasons in the French Top 14.
Usually deployed at full-back, he can also play at centre and on the wing.
Immelman hails from Upington in the Northern Cape province of South Africa and learned his trade in the prestigious rugby nursery, Grey College, in Free State. He featured in the under-20 provincial championships (reaching the final), Varsity Cup and Free State XV squads.
He then joined Montpellier in 2016, and helped them to a first-place regular season finish in 2018 under the guidance of former Scotland coach Vern Cotter. They reached the Top 14 play-off final where they lost to Castres at the Stade de France.
This has been a less successful season for Montpellier who have struggled at the wrong end of the table. Immelman was suspended in December for three weeks for a dangerous tackle on Wasps scrum-half Will Porter in the Champions Cup which earned him a red card.
Immelman, who has scored 13 tries in his 75 appearances for Montpellier, said the likely prospect of playing against South African teams in an expanded Pro14 was part of the attraction of signing for Edinburgh.
“I was really excited when I heard about Edinburgh being interested in me,” he said. “After five seasons in France, I was considering a new experience in another league, so it was a no brainer.
“It’s an amazing club with a lot of history and, after speaking to Richard Cockerill, the vision was clear where they saw me fitting in and how I can contribute.
“The Pro14 – especially with the potential for the four new South African sides joining next season – will be a really great league to be part of and hopefully we’ll see Edinburgh do great things.
“I just want to get there, do my best, play rugby and experience a new home, a new competition and see what I can give back to Edinburgh.”
The four South African Super Rugby franchises – Sharks, Stormers, Lions and Bulls – are expected to join the Pro14 set-up next season.
Cockerill has never hidden his admiration for South African players and Immelman will join compatriots such as WP Nel, Boan Venter, Pierre Schoeman, Jaco van der Walt, Luan de Bruin and Jordan Venter in the capital.
“We’re delighted to announce Henry has signed for us despite a number of offers from elsewhere,” said the Edinburgh head coach.
“He’s a very good player, a big physical ball carrier, with a big boot on him and will really intensify the competition for places in a number of areas in our squad next season.
“He’ll certainly add to our threat in the wide channels where we’ve already got some quality options and players coming through the system.
“We’re putting together a really exciting group for the new season, one which we hope our supporters can see taking shape and can visualise running out before a big crowd at the new stadium.”