The 32-year-old, who can count Inverness CT among his former clubs, moved to Parkhead in the summer of 2017 but the Republic of Ireland internationalist is now back at Pittodrie.
Manager Derek McInnes told the club website: "Bringing Jonny back to the club is fantastic. In light of the current financial circumstances as a result of the pandemic, this has only been possible due to Jonny being out of contract and his real desire to re-join Aberdeen.”
.png){kind=logo}
