The pair were first reported to be engaged when it was claimed that Karl proposed during the couple's vacation to Fiji in January.
Overnight, Jasmine debuted her $120,000 princess cut engagement ring at the party, with sources telling The Sydney Morning Herald that the shoe designer was "thrilled to show off her new bling and pose for pictures."
Jasmine herself shared a photo from the evening on Instagram, sitting with friends her sparkler was on full display as she leant her hand on her knee.
Karl and Jasmine met in late 2016, shortly after the TODAY host split from his wife of 21 years Cassandra Thorburn.
The pair, who officially divorced in October 2017, have three children together: Jackson, 18, Ava, 12, and River, 10.
This article originally appeared on InStyle Australia