Finch has become a feature at the top of the Surrey order in T20 cricket for the past two seasons along with England opener Jason Roy.
The 30-year-old was one of only two players at the county to hit a century in the format last season with an explosive 114 off 64 balls in a 17-run win against Sussex back in August.
Of his decision to return to London for another two seasons, Finch said: “I’m absolutely thrilled to be back at Surrey. I have enjoyed my time there these past few seasons and am really looking forward to reuniting with the lads and looking forward to a successful summer.”
Finch has led Australia in T20 cricket during 2017 and has earned a reputation as one of the biggest hitters in the short format of the game.
The 156 he scored against England at Southampton in 2013 remains the world’s best ever.
And Surrey director of cricket Alec Stewart said: “Aaron Finch is one of the leading T20 batsmen in the game and, to have secured his services for another two seasons is a great result for the club.
“His opening partnership with Jason Roy is among the most destructive in world cricket and he is now very much an integral part of our dressing room.”