LOS ANGELES — Inside Milk Studios, a marble building here on North Cahuenga Boulevard, waiters passed sushi rolls amid racks of dresses, bags and T-shirts. Outside, a starlet posed on a red carpet by a reflecting pool, wearing a crimson scuba dress overlaid with black lace. It had all the trappings of a Hollywood branding soiree, announced by a neon sign hovering overhead: “Welcome to the Rebelution.”

But the starlet in question was no blushing waif. She was Rebel Wilson, the Australian actress and comedian known for her ribald turns in “Bridesmaids” and “Pitch Perfect.” She was there to promote her new plus-size collection for Torrid, a design and retail company that caters to sizes 12 to 28.

The line, which arrived in stores Nov. 1 and features about 30 pieces from $16.50 to $98.50, embodies the idiosyncratic moxie known to Ms. Wilson’s fans. There are T-shirts printed with gangster koala bears (nods to Ms. Wilson’s home country and her love of hip-hop), jackets stitched with varsity letter R’s (a homage to her boarding-school days) and sweatshirts emblazoned with her first name.

That Ms. Wilson has entered the fashion game signals not only her unconventional stardom but also how far the plus-size industry has evolved in recent years. As the mainstream fashion world has continued to neglect women of larger sizes, often relegating them to upstairs corners of department stores, a lively alternative industry has sprung up to fill the gap.