Winning the opportunity to be a college student guest editor of Mademoiselle’s August 1964 issue (a competition held every year and previously also won by Sylvia Plath and Joan Didion), Johnson immediately parlayed this into a job illustrating for the magazine. Her quirky line drawings and personal style drew attention—within months she was designing for a shoe company, illustrating for other magazines and ad companies, and planning her own sweater business. These knit designs were pitched by Mademoiselle’s fashion editor to Paraphernalia, “a determinedly with-it New York boutique” that was opening in September 1965 and backed by the mass-merchandiser Puritan Fashions—Johnson was hired immediately to be an in-house designer at only 23-years-old.

Recognized as a key designer of the “Youthquake” movement, Johnson designed for women who lived the same lifestyle as her—always out, running from party to Max’s Kansas City to another party, open to every new idea and opportunity. Her designs were uninhibited, at first quite mod with abbreviated swinging hemlines and made of mirrored or Day-Glo fabric. When she started at Paraphernalia she was given free rein to design from her imagination yet over time the corporate heads behind the brand became more involved and demanded she follow fashion trends, not set them. Johnson left Paraphernalia in June 1968 and said at the time: “In the last six months, I didn’t know who I was I felt I had lost control of my work. My stuff is better when it isn’t watered down. But I don’t control what’s done with it, how it’s presented. And fashion’s become a drag again. It’s become who can knock off what and how fast.” Very aware of her own talents and strengths, Betsey knew her particular style served a clientele that wanted affordable, easy-to-wear clothes and who were uninterested in Paris and what the magazines said: “Fashion is really healthy and human right now. It doesn’t happen out of Paris couture pattern books any more.” In the summer of 1969 she started designing the wholesale line for Alvin Duskin of San Francisco while at the same time opening a boutique with two friends—Betsey, Bunky and Nini’s, on East 53rd street (just down the block from Norma Kamali’s first store).

In her quest to be able to design “what she believed in,” Johnson signed with the sportswear house Alley Cat in January 1970. By contracting with a merchandiser like Alley Cat, Johnson was seeking to bring her message to the masses: “I try to design something by the thousands that looks like it’s handmade.”Transmuting the view that mass designs had to be boring, she said she enjoyed “the escape” of costume clothes yet sought to produce them at a moderate-to-medium price point. Alley Cat became her laboratory where she experimented, blending influences and diverse ideas into a cheap, colorful juniors collection. At Paraphernalia she had attempted to bring in some retro influences (such as Biba-like 1940s shoulder pads and Edwardian high-necks) but these innovations were too early and fell-flat with mod-oriented consumers. By the early-1970s fashion on the whole had caught up with her interest in the past and Johnson’s modern, comfortable cotton clothes that incorporated quaint historical details were an immediate hit with store buyers and customers.

What stands out about Johnson’s clothes for Alley Cat is the way she combined a cacophony of influences, patterns and colors into a cohesive whole. The designs were often whimsical—nursery animals prints, sweaters woven with sunsets, calico apron dresses—and belied her personal interest in using fashion as a joyful expression of life. When discussing her fall 1971 collection, Johnson clearly articulated how her designs were a renunciation of the “total looks” created by other designers: “We’re not into one thing right now. I want to do all the ideas I have. I see people wearing the little printed flannel shirt with a bird-in-nest jacquard sweater over Fred Astaire big-pans with the printed Turkish flannel quilted cut-away jacket. Or I see them wearing the cut-away jacket over the Medieval flannel dress… real opposites instead of the Civilized planned look.” Each collection included a multitude of different silhouettes, cuts and garment types.

Produced as a juniors line, Alley Cat was primarily featured in younger, less elite magazines—Seventeen, Cosmopolitan, Glamour and her alma mater, Mademoiselle—with Vogue and Harper’s Bazaar often including the pieces in their “More Dash than Cash” pages. Johnson’s Alley Cat designs should not be relegated in memory as just a cheap brand; though it was affordable it was also highly influential. A year into her tenure at Alley Cat, WWD was already describing Johnson as “the most knocked-off designer on Seventh Avenue.” Just like other the breakout boutique designers of the 1960s (such as Mary Quant, Biba, Dorothée Bis, and both herself and Emmanuelle Khanh at Paraphernalia), with Alley Cat Johnson was helping set the trends of the early-1970s. Of greatest influence were likely her sweater knits. Johnson’s earliest design ideas in 1965 had revolved around shrunken poor-boy sweaters (an idea brought to worldwide fame in the following years by Bis and Sonia Rykiel)—revisiting this style for Alley Cat, she produced them in crazy jacquard patterns (ducks, girls and boys names, shells and fish) and sewed them into every style imaginable: mini and maxi dresses, wrap skirts, bellbottoms, knickerbockers, hot pants and matching caps. The high and lower ends of the market followed suit, copying them and leaving Johnson on a constant chase for new pattern ideas. Proving her importance to the American fashion industry, in 1971 Johnson was the youngest designer ever to be awarded the Coty. She shared the award with Halston, whose designs were at the far end of exclusivity and price from hers.

When her contract expired January 1975, Johnson left the firm; then pregnant with her daughter, she felt hemmed in by the responsibility of creating huge 150-piece collections for Alley Cat. After several years spent freelancing and feeling dissatisfied with fashion, the punk movement reenergized her and led Betsey to open her own company in 1978. Throughout the ups and downs of having her own company (which declared bankruptcy in 2012), Johnson has remained solidly aware of producing clothes that are happy, affordable and wearable, and has stood by a tenet of fashion she gave in 1971: “Anything and everything is right if it just looks right to you… and if it’s something you really believe in.”