Hulanicki’s first encounter with her new customers was at 10 o’clock on the Saturday morning it opened. "...the curtains were drawn across the window… the shop was packed with girls trying on the same brown pinstripe dress in concentrated silence. Not one asked if there were any other styles or sizes," Hulanicki remarked.
The brown pinstripe dresses were being stored in the shop because Hulanicki’s apartment was overflowing with boxes of clothes for their mail order service. Fitz-Simon dropped Hulanicki at the shop and went to pick up more dresses, Hulanicki went to the bathroom and when she came back the shop was packed. "The louder the music played the faster the girls moved and more people appeared in the shop. I had sold every dress by 11." After the last dress had been sold, people were still lining up inside waiting for the next delivery.
The shops' main appeal was that an average girl in London could, for less than 10% of her weekly earnings, share the look of popular icons of the time such as Cathy McGowan, the 'Queen of The Mods' and presenter of Ready, Steady, Go, a popular TV music show. What was seen on TV on Friday night could now be bought on Saturday and worn that night. It made you feel special. As the Biba style (tight cut skinny sleeves, earthy colours) and logo became more and more recognisable, the more and more people wanted to be seen in it.
The second store in Kensington Church Street opened in 1965 and series of a mail-order catalogues followed in 1968, which allowed customers to buy Biba style without having to come to London.
The next move, in 1969, was to Kensington High Street, into a store which previously sold carpet. Again, it was unique; a heavenly mix of Art Nouveau decor and Rock and Roll decadence. On May 1, 1971, a bomb was set off inside the store by The Angry Brigade, an anarchist group
In 1974, the store moved to the seven-storey Derry & Toms department store, which immediately attracted up to a million customers weekly, making it one of the most visited tourist attractions in the city of London. There were different departments, and each floor had its own theme, such as a children's floor, a floor for men, a book store, a food market, and a "home" floor which sold items such as wallpaper, paint, cutlery, soft furnishings and even statues. Each department had its own logo or sign, which was based on the Biba logo and had a picture describing the department; these were designed by Kasia Charko. One of the most popular departments was a "Logo Shop" featuring merchandise adorned with the Biba logos and pin-up art, such as playing cards, match books, and coloring books. The store had an Art Deco-interior reminiscent of the Golden Age of Hollywood  and non-traditional displays, such as a giant Snoopy and his doghouse in the children's department, where merchandise based on the Peanuts comic strip was sold. The Biba Food Hall was also designed ingeniously, each part being aimed at one particular kind of product; a unit made to look like a dog (based on Hulanicki's own dog, a Great Dane named Othello) consisted of dog food; a huge baked beans tin can consisted of only tins of Baked beans; a can of "Warhol's Condensed Soup" etc., all foods having individual innovative units. Also at the new "Big Biba" was "The Rainbow Restaurant", which was located on the fifth floor of the department store and which was destined to become a major hang-out for rock stars, but which wasn’t solely the reserve of the elite. Also at the site was the Kensington Roof Gardens, which are still there today.