Among those attending the show in Milan was French luxury tycoon Francois-Henri Pinault, the husband of actress Salma Hayek and the chief executive of the multinational Kering, which owns Gucci.
Also present were US actress Blake Lively and US Vogue editor Anna Wintour in her trademark sunglasses, as well as Russian luxury tycoon Mikhail Kusnirovich, a Milan regular.
Fashion week, which runs until Monday, will feature 74 catwalk shows ranging from familiar names like Armani, Dolce & Gabbana, Fendi, Gucci, Prada and Versace to up-and-coming young designers.
Organisers have said they are aiming to inject more young talent into the industry, as it looks forward to 2014 when it hopes to shake off the recession.
While fashion giants have stayed buoyant thanks to booming sales in emerging markets, smaller labels have struggled after a plunge in the domestic market.
Mario Boselli, head of the National Chamber of Italian Fashion, which organises Milan Fashion Week, said the latest estimates point to turnover for the industry next year that will equal that of 2008, before the economic crisis.
"For the first time we have hopes that the domestic market will prove more buzzing," Boselli said, although he admitted that turnover for the industry as a whole for 2013 would still be down 2.5 percent from 2012.
"We are ready to do everything to return to Italy and to Milan a leading role on the international fashion stage," he said.
Thousands of young revellers packed into fashion boutiques on the eve of fashion week as DJs pumped out club music in an event called Vogue Fashion's Night Out.
Milan has to establish itself as "the most prestigious platform for young talent", Franca Sozzani, editor of Vogue Italia, said at a press conference.
Famous designers and VIP guests were expected to turn out later on Wednesday for a gala at La Scala, the world-famous opera house that is opening its doors to fashion week for the first time.
DSquared2 also had its show on Wednesday in a nightclub -- a visually stunning parade of sizzling summer wear inspired by the 1950s and locations like Acapulco.
The Canadian twin design duo, Dean and Dan Caten, said they were going for a feel of "island glamour", including lampshade hats and cat eye glasses.
Particularly memorable were the bathing suite-style cocktail dresses and lace skirts, with models sipping cocktails and sashaying down the catwalk to the sounds of the mambo and the cha cha cha.
Alberta Ferretti brought a touch of sophistication to the catwalks with a very feminine collection of long, light dresses that made the models seem like the subjects of a pre-Raphaelite art.
But the strong point of the show were a series of brilliant-white tunic dresses with embroidered floral edgings and ribbon belts that had a folk feel.
French-owned Fendi and pride of Milan Prada take to the catwalks on Thursday, followed by Etro and Versace on Friday.
Saturday it will be the turn of Bottega Veneta, Roberto Cavalli, Jil Sander and Moschino, then Missoni and Salvatore Ferragamo on Sunday.
Dolce & Gabbana will also be showing on Sunday although they are not on the official calendar following a reorganisation of fashion week and a spat with Milan authorities over a tax fraud case they are involved in.
Giorgio Armani and Gianfranco Ferre will round off the week on Monday.
Italian fashion house Costume National will also be returning to Milan after more than two decades of showing in Paris -- a gesture of solidarity from designer Ennio Capasa to help out Italy at a time of economic hardship.
One of this year's most highly anticipated newcomers is established luxury shoemaker Tod's which is showing its first ever womenswear collection on Friday designed by Alessandra Facchinetti, formerly at Gucci.