Aberdeen manager Jimmy Thelin told his club’s website: “Kevin made a real impact during his time here last season and his arrival provides a long-term solution to our attacking options.
“He has proven goalscoring ability and we were really starting to see all that Kevin can offer towards the end of last season. As a Scottish international, he helps enhance the identity of our team, which we continue to develop.
“What is most important to us is that Kevin really wanted to be here at Aberdeen. He knows what we are looking to achieve here and he wants to continue to be a part of that.”
Nisbet scored 13 goals in 38 appearances for Jimmy Thelin’s side, helping them lift the Scottish Cup.
On his return to Millwall, he has made one start and three substitute appearances this season but says “it’s great to be back” at Pittodrie.
“Ever since I left, it was always in the back of my mind that I wanted to come back, but I am here, so I’m delighted,” he said.
“The way last season finished, I felt I was really hitting my best form and I felt at home here.
“The gaffer really helped me improve my game last season. I want to keep improving and this is the best place for it.
“I’m feeling fit, I’m mentally and physically ready to come and help the team, on and off the pitch.”
Glasgow-born Nisbet started his career with Partick Thistle and also played for Raith Rovers and Dunfermline Athletic before joining Hibs.
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