The couple first got engaged in April, but Cutler broke up with the reality star months later.
Recent rumours that Cavallari and Culter had got engaged again were swiftly denied by Cavallari.
However, the Hills star has now taken to her Twitter to confirm the news, writing: "This time its official..Jay and I are engaged again :)"
At the time of their break-up, a source claimed that Cavallari was "absolutely devastated".
The insider said: "She was planning her dream wedding, the date was set, the location - everything was set. She's in shock that the dream wedding she was planning is going to end this way."
Watch Kristin Cavallari's first dance on Dancing with the Stars below (US only):