The rugby star, 32, will allegedly be paid £250,000 if he agrees to enter the jungle, according to the Daily Star.
Smith and Minogue, who have 1-year-old son Ethan, have recently been combating rumours that their relationship is on the rocks.
"Kris is always referred to as Dannii's boyfriend and he thinks doing I'm A Celebrity... would be a good chance to show everyone who he really is," said a source.
Smith joins '90s child star and Lindsay Lohan's former lover Aaron Carter in this year's rumoured lineup, alongside Imogen Thomas and Dollar singer Thereza Bazar.
I'm A Celebrity... returns to ITV1 in November.