Beyoncé Wears Low-Cut Dress, Shows Off Flowing Locks in Hair Care Ad

Beyoncé giving fans the secret to getting flowing locks just like her ... pushing a new hair care product in a fabulous, low-cut outfit.

The singer-songwriter appeared in a clip for her brand CÉCRED -- posted Sunday -- holding a vial of amber liquid and then running her hands through her hair ... shaking it around to show its bounce and volume.

She's revealing quite a bit in the clip ... showing off her chest in a low-cut outfit -- before passing the bottle of CÉCRED to her mom, Tina Knowles, who passes it to the next person and so-on and so forth.

Ultimately, it ends up in an Ulta Beauty store ... where, CÉCRED writes fans can go buy it now to get their hair lookin' just like the Queen Bey.

Beyoncé's still flying high from her numerous Grammy wins this year ... including winning Album of the Year for the first time with her country debut, "Cowboy Carter."

Bey's hittin' the road soon enough too ... heading out on a world tour at the end of this month that will take her from L.A. and Chicago to Paris and London and more.