The actress won the competition after beating out third placed contestant Bristol Palin and runner-up Kyle Massey on the ABC series.
Grey and partner Derek Hough were the longtime favourite pair of the judges and were the only couple to achieve perfect scores on multiple occasions throughout the competition.
Speaking after the win, Grey said: "I didn't think I was going to make it tonight and I'm so glad I did!"
Hough added: "I can't believe it!"
The episode saw the return of all 12 original celebrities as well as their professional dance partners, each of whom participated in several dance routines throughout the broadcast.
David Hasselhoff took to the stage for a rendition of the Baywatch theme song and an accompanying dance. Rick Fox and Kurt Warner also challenged one another to a staged sports-themed dance-off to determine who was the better dancer.
Florence Henderson and Margaret Cho joined one another on stage for a double performance to Barry Manilow's 'Copa Cabana' while The Situation danced shirtless in a light-hearted number to Right Said Fred's 'I'm Too Sexy'.
Brandy also returned for an encore performance of her popular quickstep.
Christina Aguilera appeared for a special performance of 'Show Me How You Burlesque', from her new film Burlesque, as well as hit single 'Beautiful'.
Dancing With The Stars airs on ABC.
> Click here for our recap of tonight's Dancing With The Stars finale