LuLaRoe LLC’s primary clothing supplier sued the leggings company over $49 million in unpaid bills and accused its top executives of looting its assets to buy exotic cars, private planes and real estate.

The Long Beach, Calif., supplier, Providence Industries LLC, said Thursday that LuLaRoe hadn’t paid its bills for seven months while its principals, Mark and DeAnne Stidham “lavished themselves with luxurious lifestyles” by misappropriating money belonging to creditors.

LuLaRoe,...