The pair have recently sparked romance rumors after fans started noticing their flirty comments to each other on social media, months after Bilson appeared on an episode of Viall's podcast, The Viall Files, in July.
Whether the pair's connection turns into a relationship remains to be seen, but a source close to the situation tells ET that Bilson and Viall have stayed friendly and "kept in touch" since she appeared on the podcast.
Viall confessed on the episode to having a crush on Bilson, and ET's source says that hasn't changed. According to the source, the former Bachelor finds Bilson "smart, fun and attractive."
During an interview with ET last month, Bilson said that dating was not a priority for her as she raises her 4-year-old daughter, Briar Rose, with ex Hayden Christensen. However, she always makes time for The Bachelor.
"I have 'me nights' that are very short because I have to get to sleep and I have to wake up with my daughter, where I take baths or make time to watch any of the Bachelor shows, because that is my 'me time,'" Bilson said, before clarifying her complimentary comments about another Bachelor Nation alum, Tyler Cameron.
The O.C. star had joked with Viall, 38, about finding the 26-year-old Cameron attractive, but insisted to ET at the time that she wasn't interested in a date with the contractor.
"He was definitely my favorite and my pick, I should say, while watching. I think most people enjoyed watching him," said Bilson, 38. "[But] no. I mean, I could have birthed him, so the answer is there. [Laughs] I'm just kidding! He's very young. But he's definitely easy on the eyes."