Between the two of them, Hollywood stylists Simone Harouche and Jamie Mizrahi have more than 20 years of experience bedecking the bods of A-listers, including Kim Kardashian, Katy Perry and Miley Cyrus.

That means they’ve taped a lot of boobs.

This fall, they launched their own expansive collection of underpinnings called The Kit: all kinds of stretchy, smoothing, securing tools, inspired by the ones Mizrahi and Harouche use during fittings.

It’s already beloved by celebs: Kate Hudson, Karlie Kloss and Kourtney Kardashian have all posed in their Kit undies on Instagram. But the items — which start at $18 — are meant for mere mortals. There’s a style of seamless tap shorts beloved by J.Lo for coverage under super-short skirts, six (!) different bras to accommodate different necklines and boob tape that promises to stay put for an entire four-hour awards show.

You’ll even find a “pretty sticky” adhesive thong, which is less scary than it sounds — and handy for rocking body-conscious silhouettes sans panty lines. “Just tape it on the front, tape it on the back, there’s nothing on the sides and you’re good to go,” Harouche said.

So even if you’re not posing in a skintight gown at the Met Gala or belting out a hit in booty shorts on stage, there’s much to learn from the red-carpet veterans on what to wear underneath sexy holiday party looks. Here, the Post’s stylists take their products for a test run on some fierce and festive silhouettes.

__

A low neckline and lots of leg

The secret weapon for pulling off majorly plunging ensembles is The Kit’s cotton Bandage Tape ($16 for nearly 30 feet of tape) which is surprisingly versatile. “You can create different kinds of coverage, following the neckline of the dress and taping your breasts to make a ‘bra,’” Harouche said. “Once you get the hang of it, it can be your best friend.”

With this draped top, for instance, our stylist took a length of tape around our model’s neck and straight down over both breasts, halter-style, which adds lift and also allows the front of the blouse to hang smoothly.

And when you’re baring your gams in super-high slit, it’s time to pull out the big guns — or rather, the extremely small guns. “The Adhesive Thong ($18) is an amazing little item, because you can wear something that shows the entire side of your body and you won’t see an undergarment,” Harouche said.

Slinky backless tops

When you’re bringing sexy back, pasties are your best bet. “The petal kind are more generic and widely used, but I really like our X-Nipple Covers ($14) because I think they adjust more to your body, and there aren’t as many ripples and wrinkles to see through your clothes,” Mizrahi said — an especially helpful tip when you’re working with a slinky silk or satin halter top under which a standard strapless bra might show.

Harouche, whose client Miley Cyrus has daringly donned visible pasties of all shapes and sizes, agrees: “From working with many different women and breast shapes, I’ve found that the X’s lay a little better, though they are maybe a little more intimidating to look at!”

Deep V-necks

For moderately plunging necklines like the one on this brocade frock, a low-cut bra like the brand’s Triangle Underwire Bra ($58) is your best bet. “It offers support and lift, and also has the ability to be a halter, so if it’s one of those more narrow necklines, you can also use it that way,” Harouche told us. The front closure of this dress actually hit just at the center of the bra without gaping where it wrapped — score!

Body-conscious clothing

Bold, high-waisted satin pants are a professional and polished upgrade to the clingy, blingy party dress this season. To pull them off, you definitely need seamless undies to avoid pesky panty lines. “The Seamless Thong ($22) is going to be the most invisible under something that’s really tight,” said Mizrahi. (Our stylist also found that the adhesive thong works well with these pants, too!)

Bandage tape, $16, and adhesive thong, $18, both at TheKitUndergarments.com

Alice + Olivia “Aurora” draped shawl-collar wrap top, $330 at Neiman Marcus, 20 Hudson Yards; BB Dakota “Shiny Dancer” skirt, $88 at Shopbop.com; Badgley Mischka “Claudette” sandals, $185 at Bloomingdales.com; “BSWAGGER” clutch, $70 at SteveMadden.com; Pendant necklace, $429 at Swarovski.com; Necklace, $168 and ring, $69, both at KateSpade.com

X-Nipple covers, $14 at TheKitUndergarments.com

“Tatiana” top, $128 at TheReformation.com; Skirt, $49.90 at Zara.com; Badgley Mischka heels, $198 at Nordstrom.com; “Elton” silver cuff, $70 at KendraScott.com; Crystal bubble drop earrings, $325, and silver faux leather headband, $65, both at LeleSadoughi.com

Seamless thong, $22 at TheKitUndergarments.com

Brock Collection top, $179.99 at Century 21, 21 Dey St.; Alice + Olivia “Dylan” pants, $330 at Neiman Marcus, 20 Hudson Yards; “Edulla” pumps, $95 at AldoShoes.com; “Alaina” clutch, $68 at NinaShoes.com; Cuff, $499 at Swarovski.com; Earrings, $295, and ring, $225, both at AlexisBittar.com

Triangle underwire bra, $58 at TheKitUndergarments.com

“Ginger” dress, $495 at ba&sh, 403 Bleecker St.; “Savannah” heels, $395 at LoefflerRandall.com; “Amorie” clutch, $65 at NinaShoes.com; Earrings, $215, and bracelet, $295, both at AlexisBittar.com; “Nirvana” ring, $189.00 at Swarovski.com

Bandage tape, $16 at TheKitUndergarments.com

ROTATE “Number 46” jumpsuit, $310 at Shopbop.com; Metallic mesh bag, $59.99 at Mango.com; Earrings, $255 at AlexisBittar.com; 18k gold plated cuff, $127 at Missoma.com; Retrofête “Luna” skirt (worn as headpiece), $295 at Revolve.com

Stylist: Johannah Masters

Model: Shaya/Click