Jersey captain Alex Rae will retire from playing at the end of the season to become the club's forwards coach.
The 30-year-old replaces Steve Boden, who is joining Yorkshire Carnegie.
Rae has spent three years as a player with the Championship side and became captain when he joined.
"I've had ambitions to eventually coach when my playing days were over and, although the chance has come sooner than expected, it's a fantastic opportunity for me," said Rae.
"I've got big shoes to fill in succeeding Steve Boden - he's taught me a lot and leaves the club in a good place, although there'll be pressure to maintain and improve the club's status after the last two seasons.
"Harvey (Biljon, Jersey head coach) and I have worked really well together - I know what he's about and his ambitions and I think we'll make a good team."
The former Wasps, Northampton and Bedford lock has coached Jersey's junior teams for the past two seasons and his final Championship match will be Saturday's fixture with Yorkshire Carnegie at St Peter.
"We have had a very high calibre of applicant, and gave serious consideration to a number of those who stepped forward," said Jersey chairman Bill Dempsey.
"Ultimately we saw someone in Alex whose attitude and commitment are outstanding and will help drive the club forward in our fifth Championship season and beyond."
Rae's swansong could be the Siam Cup against Guernsey on 7 May if he is selected - he is eligible as he has been with the island squad for the past three seasons.
"Alex's leadership skills have been a great asset to the club over the past three seasons, and will leave him well-placed to make the transition to coaching," said Jersey boss Harvey Biljon.
"He's spent seven years in the Championship and knows the division inside out, and I know he'll be working really hard from the word go."