Scott McKenna has signed for English Championship side, Nottingham Forest in a deal that could be worth a reported £6m, made up of £3m plus substantial add-ons.
Scott was left out of the squad in the defeat to Motherwell on Sunday.
Manager, Derek McInnes said: “Scott is clearly a player who has approached his career to date in the correct manner and quite rightly, he has now got his reward.
“We have had the benefit of this in our first team and whilst from a football perspective it is sore to lose a player of his quality, we felt this was the right time for Scott to move on. He has had a real football education at our Club and he always approaches his work in a correct and professional manner. Scott is exactly the type of player and person we strive to develop at Aberdeen and is the ideal role model for other young players.
“Like any of the players that leave we always keep an eye on their progress with a sense of pride and I’ve not doubt he will go on to have a great career.”
Derek McInnes explained earlier in the week: “We made succession planning with Ross and Hoban coming in short-term.
“We weren’t encouraging bids but we expected bids as soon as the Championship started.
“His stats are right up there in our league.
“We were allowed to bring in Tommie and Ross to deal with a McKenna leaving.”
McKenna, who was the subject of a £7million bid from Aston Villa two years ago, came through the ranks and McInnes expects him to smash it in England.
“Scott was always going to move at some point. He’s a player with 16 caps and at the age of 23 he’s only going to improve.
“He’s not just a good player, he’s a brilliant person and a great boy and I’ve enjoyed working with him. It’s always a heavy heart when you lose good ones.
“But he’s one who’s deserving of another opportunity to push on.
“Wherever he ends up he’ll have a good career as he treats everything properly, whether it’s a passing drill or recovery after games.”