OnlyFans stars Sophie Rain and Piper Rockelle are giving Miami Swim Week a serious temperature spike ... parading around in tiny bikinis while getting dolled up for their big week!

Roll the footage ... Sophie and Piper were front and center inside the buzzing prep suite -- organized by Creators Inc. CEO Andy Bachman -- trying on different bikinis while cameras rolled.

Sophie showed off a series of curve-hugging looks, from an animal print string bikini to a flirty white-and-red two-piece ... while Piper rocked her own barely-there lineup that left very little to the imagination.

The video turns into a full-on bikini try-on party ... with the duo swapping looks and striking poses surrounded by models and racks of swimsuits.

The two weren’t just getting ready for Swim Week ... they were treating it like their own personal runway -- like an Instagram explore page come to life!