The painting, by Swiss-born Victorian artist Marc de Jong, was among 849 works submitted for the prestigious prize.
It captures Petersen - and colleague Anton Enus - at work in the World News Australia studio.
"I sat for Marc a couple of times - at a cafe, and he even did sketches of me driving," Petersen explains.
"Then he came to SBS and spent a few hours in the studio and the green room."
Petersen said she was honoured and excited to feature among the shortlisted works.
"I was very flattered to be asked, and then there's a bit of anticipation as to how it's going to turn out - whether you're going to like what you see.
"It's not a conventional portrait, but I really like the fact he's pushing convention.
'No hiding' excitement
"I haven't been very cool about it at all - there's no hiding my excitement, I've been texting friends and everything."
Petersen said she was thrilled that up-and-coming artist de Jong had made it to the shortlist of just 34 portraits.
"It was his first attempt at the Archibald this year, after he was in the Wynne and Sulman prizes last year, so he's doing really well," she said.
The Archibald Prize is one of Australia's most prestigious art awards.
Established in 1921, it features work from some of the country's most distinguished artists.
The 2010 winner, who receives $50,000, will be announced next week.
On Wednesday, Sydney artist Nafisa was named winner of the Packing Room Prize, for her portrait of rock historian Glen A Baker.
The large-scale black and white work was chosen by backroom staff at the Art Gallery of New South Wales.
