The reality TV beauty - who is the face of the denim brand - thinks the new advert, in which she showcases one of the label's new bikinis, is "amazing" but "way up close and personal".
Speaking of the huge image on Hollywood's Sunset Boulevard, in which she is posing in a black two-piece, she told People magazine: "It's gigantic. It's so big! When I saw it, I was like, 'Oh, my god, that's way up close and personal.'
"I'm so appreciative of it. I never in a thousand years thought I'd ever be up there. It's insane, but it's amazing."
The 25-year-old brunette - who used to star in 'The Hills' and now has her own VH1 show 'Audrina' - says the new campaign shows what the brand has to offer for the summer and excited to be promoting their first ever swimwear line.
She explained: "It was really about promoting the brand's spring and summer lines. Bongo has bathing suits now, which they've never had in the past. I think they really wanted to promote that, and since I'm always in a bikini, it just kind of made sense. It was an amazing shoot."
Audrina is also delighted to be representing Bongo because she remembers her mother wearing the brand when she was little and now likes to wear its clothes and accessories herself.
She said: "I love Bongo. My mom used to wear it in the '80s. It's been around forever. They have all kinds of apparel, as well as accessories. The clothes are actually cute. I don't like to just slap my name on something. I like to be involved. I need to like the product, otherwise I'm not going to represent it."