Celtic skipper Scott Brown will join Aberdeen in a player/coach role this summer.
The Dons confirmed the 35-year-old had agreed a pre-contract deal.
Brown will link up with newly-appointed Aberdeen boss Stephen Glass, whom he played with at Hibernian.
The decision will bring the curtain down on a hugely successful 14-year spell at Celtic.
Brown said on the Celtic website: "It is a huge decision to leave this magnificent club, which has been such a massive part of my life for so long, but this is a new opportunity for me and a new chapter. Celtic will never leave me and the club will forever be in my heart.
"We still have work to do this season and that will, of course, as ever be my full focus as we try to bring our fans more success."
Quoted on the Aberdeen website, Brown added: "There is no doubt I had a lot to deliberate when deciding my next steps, particularly after enjoying 14 successful years at Celtic.
"However, the opportunity to join Aberdeen, a club entering an exciting new period with my former team-mate Stephen now at the helm, was one I couldn't pass up.
"I still feel I have got a lot to give, not only on the pitch, but in a broader capacity as I embark on my coaching journey. I will be relentless in my quest for success for Aberdeen."
Glass spoke of the importance of bringing in an on-field leader when he was appointed on Monday.
"The opportunity to bring a player of Scott's calibre, a leader who has more European appearances for Celtic than any other player, is a huge coup for me and for Aberdeen," he said.
"His experience will be invaluable on the pitch and he is someone who will help set the standards we expect at this club.
"A born competitor, with a strong appetite to win, his hands-on approach and desire to nurture will hugely benefit the development of the young, emerging talent we have here.
"Scott will be a big part of my coaching team and, whilst his impact will undoubtedly be felt on the pitch, where I believe he still has much to give, I am looking forward to assisting his transition into coaching."
