As exclusively revealed by Motorsport.com, the Swiss star will return to Supercars for the first time since departing the series at the end of 2019.
She'll campaign a DJR Ford Mustang at the Repco Bathurst 1000, which she'll share with teenage sensation Allen.
The de Silvestro/Allen entry will be backed by Shell V-Power and run as #98 as a tip of the hat to Shell's premium 98 octane fuel.
“I am thrilled to race back at the iconic track in Bathurst and want to thank DJR and Shell V-Power for this amazing opportunity," said de Silvestro.
"Four years has been too long but who would have thought in 2019 that I would not be able to travel to Australia for such a long time.
"I am looking forward to teaming up with young talent Kai and I am sure we will make a great team. Of course, I also want to thank Harvey Norman and [CEO] Katie Page who have been supporting me all my career in Australia. I can’t wait to be back in Australia in September to start testing the new Gen3 car.”
Allen, who scored a breakthrough first Super2 win earlier this month, is thought to be a considered a long-term prospect for DJR.
There is even talk that he has a deal with the team beyond the wildcard, although the team declined to comment on that when asked by Motorsport.com.
Still, DJR team principal makes no secret of the fact that Allen is highly-rated by the team.
"Kai Allen is a young talent we have had an eye on for over a year now," he said. "He drove the Mustang last year on an evaluation day and I was impressed with his speed, maturity, and work ethic.
"Simona brings a wealth of experience to the team. She will be a fantastic mentor for Kai through his first Repco Bathurst 1000."
Allen, meanwhile, said it was an honour to be making his main game debut with one of the most successful teams in the sport's history.
"I’m so proud and excited to be joining DJR as part of their first Bathurst wildcard, representing the Shell V-Power brand," he said.
"I’m really looking forward to working with such a knowledgeable and well-respected team, who have seen so much success over the years.
"Co-driving with Simona will no doubt be a highlight of the year and I can’t wait to learn from her, as she is such an experienced driver.”
