Since springing from the mid-’90s female id that was the Spice Girls, Victoria Beckham has made a career of self-invention. Once a well-to-do suburban British teen who pleaded with her father to drive her to school in his work van instead of his Rolls, she became “Posh,” a hot pop property identified by the very pedigree she once shunned. The persona—that blend of cold insouciance and smoldering wouldn’t-you-like-to-know glamour—became a shield, first as an excuse for a shy, unconfident singer to opt out of vocal solos and some of her fellow Spices’ cheesier dance moves, and later as a paparazzi defense tactic. From behind that carefully constructed veil, she’s given us Victoria, the footballer’s wife, the hands-on mother, the walking brand, and—as the fashion world has increasingly come to see her—the conqueror.

When she walks into her ELLE photo shoot in Hollywood, the 37-year-old Beckham is dressed in what passes in her world as mom-duty ease: a slouchy, asymmetrical black knit Helmut Lang sweater, sprayed-on dark denim, and six-inch patent Louboutins. (“Super casual and comfy,” she says.) On her hip is three-month-old Harper Seven, her fourth child and—finally!—first girl with husband David. A quick costume change later, Beckham is in mogul mode: a cherry red, drop-waist wool dress from the inaugural collection of her new mid-price dress line, Victoria, Victoria Beckham.

Beckham has introduced sophisticated daywear and a handful of loose, unstructured silhouettes to the main line she launched in 2008, but she’ll forever be synonymous with the luxe, fits-like-a-glove dresses that first defined her brand. Tailor-made for flashbulbs but built to attract women both in and out of the spotlight, these figure-flaunting shapes—intimidating even for those who share her honed 5’3″ frame—are surprisingly woman-friendly, with two-way zippers (which adjust to the length of a wearer’s stride), hidden corsets, breathable mesh linings. “When we have Victoria’s stuff in the studio, it’s the first thing Cameron Diaz tries on,” says stylist Rachel Zoe, who met Beckham at a dinner party with Marc Jacobs and dresses celebrity clients such as Demi Moore in Beckham’s designs. “But any woman would feel sexy in her dresses.”

With that fit and its creator’s knack for self-promotion—these days she’s almost exclusively snapped in her own label and has effectively retired her rumored $1.5 million collection of Hermès Birkins to carry her own bags—Beckham sells. She launched a luxury brand mid-recession, when all conventional wisdom would have bet against her price point ($1,500 to $3,600). But her first collection sold out on Net-a-Porter within minutes; the site still runs through new stock in a matter of days, with some looks snatched up entirely in presale. When she launched her handbags in 2010, also on Net-a-Porter, a $2,700 two-tone shoulder bag was gone within the hour, soon followed by a $14,000 crocodile-skin chain purse. Sales of Beckham’s brands began 2011 up 71 percent; the year’s predicted earnings were a reported $95.6 million.

Initially, the staunchest (or snobbiest) of the style pack chalked up Beckham’s success to celebrity and connections—specifically, help from runway heavyweight friends Jacobs and Parisian designer Roland Mouret. But Beckham says that when she embarked on her new career, Jacobs was the last to know. “We went out to dinner one night, and he said, ‘I saw that you put out a collection,’ ” she recalls. “I felt embarrassed to tell Marc Jacobs that I—me, ex–Spice Girl, married to a footballer—was creating a fashion line.”

Beckham, who often serves as the fit model at her Battersea, London, atelier, says she’s immune to trends. “I just create what I want to wear,” she says. “I make what feels right.” Sometimes, what she feels can be strangely prescient: Her fall 2011 collection, which featured her loosest (and most bump-friendly) silhouettes yet—a blue gazar cocoon dress and a billowing clay-colored cashmere sweater­dress—was completed just as she learned she was pregnant. The new secondary line was made while she was pregnant with, she was told, a boy—but her hormones knew better; she traded her signature hourglass mystique for young, flirty frocks she says represent her “inner girl.” Friend and fellow high-profile designer/wife Katie Holmes trusts Beckham’s instinct too. “We go to the same events, and we’ll call each other to ask, ‘What color are you wearing?’ ” says Holmes. “I’m always interested in what she’s liking for the season.”

With its girlish, candy-colored ’60s A-lines, Victoria, Victoria Beckham—despite the name—represents the designer’s biggest leap to date from her own closet, starting with the $450 to $1,250 price point; it took months to find affordable fabrics that met Beckham’s standards. The cat print on a caramel crepe de chine tunic (Beckham dressed her daughter in a custom miniature version at the shoot) was inspired by feline-loving indie comics heroine Emily the Strange, whose poker face could rival Beckham’s own public persona. It’s partly a wry inside joke with her fans (“I’m quite aware of people’s preconceptions, but that’s really actually not me,” she says. “I do like to poke fun at myself and have a laugh”) and partly the designer’s fashion-friendly version of a pregnancy craving. “When I was pregnant, I just wanted to get lots of animals for some reason,” she says. “We talked about cats, but David said absolutely not.”

By September’s New York Fashion Week, that print was the only visible reminder of Beckham’s pregnancy (besides then six-week-old Harper, who has her mother’s dark eyes and pout). “Oh, listen, I worked at it,” she says. “I was breast-feeding, so I ate super healthy, and I worked out seven days a week. I wanted to burn all my leggings—I was adamant that by the time I went to fashion week I would be able to wear clothes.” And sure enough, hours after she debuted her newest dresses, she was photographed wearing one.