Piper Rockelle is spilling the tea on pulling a staggering $3 MILLION in just 24 hours in her OnlyFans debut ... and she’s gushing hard about the X-rated gig -- despite saying signing up was one of the most difficult decisions of her life!

The influencer told "TMZ Live" Wednesday she didn’t jump in the second she turned 18 in August, like many assumed ... she thought it through, waited a few months, and made sure it was exactly what she wanted to do before going live on OF Jan 1st.

Catch the clip... 'cause Piper calls the job a way to finally take back control after growing up under constant scrutiny as a popular child influencer.

She also delves into the financial aspect of it ... saying, yup sure, the money’s wild, but she doesn't plan on doing this job forever -- she’s single, focused on her future, and living life on her own terms, period.

Lastly, we also asked Piper about collabs and solos, and more ... exactly what is she doing that her fans are paying to see? And you gotta watch the clip to find out yourself ... 'cause we sure as hell ain't gonna give away the ending to the book! 👀