New Zealand-raised Johnson was no stranger to fashion design. She had often made her own clothes and formal gowns before moving to Australia in 1989 to study graphic design in Melbourne.
But before her wedding dresses sash, Johnson's chosen profession was in advertising; she worked in London for several years on international branding and campaigns for companies such as Moet & Chandon, Hilton international hotels and the Independent Television Corporation.
''The design work in London was amazing,'' she says. ''Having the opportunity to be exposed to people who had amazing creative minds was a whole new level of learning for me and I soaked it up like a sponge.''
She moved back to Sydney in 2000, inspired to do something similar for herself.
''There was definitely the bug of wanting to do something of my own creatively,'' Johnson says.
At first that was the boutique graphic design studio Milk, which she opened that year with clients that came to include Westfield and McDonald's in Europe and Britain.
But she couldn't get glamorous gowns out of her mind. ''I remember sitting in the studio one day and I just had this really clear picture in my mind of a beautiful red evening gown,'' she says.
So she began designing garments on the side.
Johnson went full-time with fashion in 2005, when she launched Johanna Johnson designs and opened a store in Paddington.
After her own trials and tribulations with allure wedding dresses shopping, providing exemplary customer service was essential.
''Looking for a gown is an investment and a very emotional experience,'' she says. ''No one offered my mother a glass of water or even a cup of tea, let alone a glass of champagne, when we were looking. You were lucky if you were offered a seat.''
Champagne, tea and plenty of time to muse over options are mandatory at Johanna Johnson but it is the gowns themselves that are most striking. The collection in store at present is inspired by the 1920s and '30s and comprises silk gowns incorporating French lace and beading, which are all finished by hand. The attention to detail and use of luxury fabrics are what distinguishes them from others on the market, as is an obsession with the golden era of Hollywood glamour that has dominated Johnson's label since its inception.
''Old Hollywood is such a timeless and elegant era,'' the designer says.
''You don't often see gowns from that time where you think, 'Oh, that was a mistake'.''
The irony of Johnson's obsession with old Hollywood is that it's now young Hollywood that is clamouring for her classic designs.
Emily Blunt, Hailee Steinfeld, Jessica Biel and Jessica Alba are among the stars who have called on Johnson for red-carpet gowns but her most memorable moment to date was dressing trumpet wedding dresses in a heavy silk satin gown embellished with Swarovksi crystals for the Emmys in September.
As soon as images of the Mad Men star in the Sydney designer's modest wedding dresses flashed around the world, Johnson's online sales jumped.
''The Christina Hendricks exposure has been really great but the people (fashion agents) in Los Angeles said to me, 'You can have all this exposure on celebrities but unless you have a product that surpasses the quality of Armani you can't do anything with it'. So to have them believe in it on that level and get that recognition for the quality has been lovely,'' she says.
The designer is now capitalising on the global interest sparked by September's media coverage with a new Lifestyle range of ready-to-wear fashion, lingerie, body products and swimwear that arrives in her Paddington store and will also be sold online from next week.
''I realised there were a lot of people following the label now that weren't necessarily about to get married but who still had important occasions in their lives,'' she says.
''You're going on a holiday and you want to treat yourself to a pair of comfortable ballet flats, you have a christening and you want a beautiful christening blanket or you want to gift your bridesmaids some beautiful lingerie,'' she says.
While the 26 products in the range have a far more affordable price point than Johnson's premium line (French lace backless wedding dresses and simple silk gowns in the lifestyle range are available from $330), the designer is adamant her core philosophy runs through the collection of luxury basics.
''These are items that will last for more than a season, so they are an extension of our bridal range being heirloom pieces that you can hand down or come back to,'' she says.
''My focus at the moment is not to dilute the DNA of the brand and what we are known for.''
On that note, while Johnson is planning to open stores in London, New York and Los Angeles to cater to demand that continues to grow, she has no plans to move her production offshore.
''colored wedding dresses is made in the studio upstairs [above the Paddington boutique],'' she says.
''It's made the prices a little higher because we are not producing offshore but it's a selling point overseas that it is not made in China but all made in Australia.''
By now, most Twi-hards have already seen Bella Swan (Kristen Stewart) stroll down the aisle in her highly anticipated wedding to Edward Cullen (Robert Pattinson).
But, what they may not have seen are these fresh images of Bella's sweetheart wedding dresses (along with a few fun facts about the gown to boot).
MORE: Breaking Dawn Premiere: Twilight Stars Vamp Up the Red Carpet!
Twilight Saga: Breaking Dawn, Part 1, Robert Pattinson, Kristen Stewart Wedding Andrew Cooper/Summit Entertainment
The classic wedding dresses, custom fitted for Stewart, was created out of crepe satin and French Chantilly Lace by famed designer Carolina Herrera, who has fashioned organza wedding dresses for the likes of Renee Zellweger, Mariska Hargitay and Christina Hendricks.
And Twilight novel series scribe, Stephenie Meyer, personally selected Herrera for the job.
"My favorite designer, Carolina Herrera, did the vintage wedding dresses," Meyer said. "I wanted the mermaid wedding dresses to be something special, not something that you're going to see every day. I love what Carolina did with it, she came up with a stunning concept. It's similar to what I envisioned, but with added elements."
But that's not all.
MORE: Robert Pattinson vs. Kristen Stewart: The Battle of the Post-Twilight Flicks!
Twilight Saga: Breaking Dawn, Part 1, Kristen Stewart Wedding Andrew Cooper/Summit Entertainment
Its intricate design included 152 buttons along the back of the one-shoulder wedding dresses and 17 buttons along each sleeve.
Needless to say, the halter wedding dresses didn't come cheap.
While Twilight-loving fashionistas can scoop up a replica at Alfred Angelo Bridal Gowns company for $799, the real wedding gown, which took four seamstresses and six months to complete, has an estimated value of $35,000.
For those willing to spend big bucks for the real thing, however, Herrera is planning to include the design in her 2012 collection via her CHNY boutiques next year.