Kanye West's wife joined him Thursday at his store in Los Angeles -- and Bianca was wearing more clothing than usual ... though she didn't let the extra material stop her from showing off a tasteful amount of cheek.

Check it out ... Bianca's steering clear of her trademark see-through tops and bottoms, while managing to play a little peek-a-boo with her boobs and derriere.

Of course, in Bianca world, this outfit would qualify as her dressing like a nun.

Kanye and Bianca had company for this particular public outing, but that hasn't stopped her from baring it all before ... so it's interesting to see her toning down the in-your-face nudity aesthetic she's become famous for.