The Hollywood actress played Donna Freedman on the programme between 2008 and 2011 and became a hugely popular character on the show.
WATCH: Margot Robbie accepts BAFTA for Brad Pitt with controversial speech
The news of Margot's return was announced on the soap's Twitter account with a post that read: "Surprise!
"You didn't think we were done did you?!
"We're thrilled to share that Margot Robbie, Jesse Spencer, Delta Goodrem, Kym Valentine and Carla Bonner will all make an appearance in our finale!"
Fans took to the comments to react to the news, praising Margot for returning to the soap that launched her acting career.
Margot is returning as Donna in the soap's final episode
One person tweeted: "This is so wholesome, I love actors returning to their roots or going back to the shows that helped their big breaks," while another added: "I'm American so I've never seen this. But it's really cool of her to do this!"
A third person commented: "Margot Robbie deciding to appear in the finale of #Neighbours has made my day. Actually back to where it all started and where MANY Australian girls' love for Margot Robbie started. Long live Donna Freedman."
Other fans were simply overjoyed to learn that Donna would be back on their screens, with one person tweeting: "Margot Robbie returning to Ramsey Street for the @neighbours finale has made my night! Could actually cry, Donna was my favourite character when I was little."
Margot rose to fame playing Harley Quinn in Suicide Squad
Margot left the show to pursue a career in Hollywood and has since become one of the industry's most well-known faces, rising to stardom following her roles as Naomi in The Wolf of Wall Street and Harley Quinn in Suicide Squad.
The 32-year-old has also received critical acclaim for many of her performances, earning two Academy Award nominations for her roles in I, Tonya and Bombshell.
Like this story? Sign up to our What to Watch newsletter to get other stories like this delivered straight to your inbox.