The fashion designer and singer, 39, opened up in a new interview about the former couple's reality show, which aired for three seasons before their marriage ended.
"We were newlyweds," Simpson stressed to Ryan Seacrest on his radio show, "On Air! with Ryan Seacrest" via People. "It was our first time even living together. I was a virgin."
The mother of three revealed it was actually her dad Joe Simpson's idea for the couple to take part in a reality series. Her father also formerly worked as her manager.
"I really want people to understand you and know that you're human,'" Jessica recalled her dad telling her.
Simpson was just 22 years old when the MTV series became wildly popular. Despite the couple's marriage ending after four years, Simpson now credits the show as the launching pad for her career.
"[The show is] what launched my brand," Simpson told Seacrest. "Absolutely I would go back and do it all over again. It's never something I wouldn't do again, I just, you know, maybe wouldn't have done a third season."
Simpson released her first memoir, "Open Book," earlier this year, where she got real about the highs and lows of her romance to Lachey and came clean about her substance abuse.
In an interview on NBC's "Today", Simpson revealed just how bad the tension between her and Lachey was before the show ended.
"I would watch episodes bac,k and I didn't like what I saw,'' she told Hoda Kotb. "I saw what people were laughing at and what was loving about it, but I also saw a lot of eye-rolling and that wasn't just editing."
In "Open Book," Simpson wrote that things were worse when the cameras weren't rolling.
“We were young and pioneering our way through reality television, always mic'd and always on,” Simpson wrote in the memoir. “We worked and we were great at it but when it came time to being alone, we weren’t great at it anymore.”
Today, Simpson is happily married to former professional football player Eric Johnson. The two share daughter Maxwell, 7, son Ace, 6, and Birdie Mae, 11 months.
Lachey has been married to TV personality Vanessa Minnillo since 2011.