The sale, which runs Tuesday through Saturday, included 10,000 coats, sweaters, suits and other garments worn by John and his partner, David Furnish.
A temporary shop, Elton's Closet, was set up in the concourse of Rockefeller Center in midtown Manhattan for the sale. Proceeds benefit The Elton John Aids Foundation.
Items included a black Versace suit with John's song titles including "Tiny Dancer" and "Rocket Man" woven into the fabric and the polka-dot Richard James suit John wore when he performed with Eminem at the 2001 Grammy Awards.
"The clothes have hardly been worn. Some of them haven't been worn," said the 59-year-old singer, dressed in a dark suit, gingham-check shirt and sherbet-stripe tie, at a ribbon-cutting ceremony Monday afternoon.
"There's the most extraordinary collection of T-shirts, your baseball caps, your shoes, from flamboyance to classic. And spend some money to help other people who desperately need their lives to be changed and improved, and you'll be doing a really good thing," he said.
This was not the first time John had cleaned his closet to raise money for his foundation. Sales have been held in London and in Atlanta, where John and Furnish have a home.
Some pieces had been plucked from the racks to be featured in the windows of the nearby Saks Fifth Avenue department store, one of the fundraiser's sponsors.
Michael Macko, Saks' men's fashion director, also eyed some pieces for himself.
"In my hands, right now, I've got two short-sleeve Prada shirts, an orange the color of highlighter cashmere blazer, and Y-3 track pants," Macko told The Associated Press.
"Surprisingly there's something for everybody. Either everybody wants to have a piece of Elton's closet for the historical perspective there probably isn't a more famous wardrobe in our lifetime or because having a fluorescent jacket that used to be owned by Elton John makes a great story," Macko said.
Pieces up for grabs also included a forest green-and-magenta Jean Paul Gaultier jacket with yellow stars, eight Versace Asian-printed silk robes and a Brioni mink-lined coat with the $8,795 price tag still attached.
There were his-and-his Gucci couture blazers, one features gold on a white background and the other silver on black; a feather chalk-stripe suit; and a silver Versace trench coat.
The items were mostly bargains, including $150 for a Gucci shirt in a swirly pattern and $30 for Nike and Adidas sneakers.
A few of the special "stage pieces" were expected to be sold for thousands of dollars.
"There's a lot of off-the-rack Abercrombe T-shirts and there's custom designer costumes," Macko said. "He (John) also knows how to pick out important and special pieces. He knows his designers and you can see he has selected the most important pieces from the collections. And he's from the `give-it-to-me-in-any-color' ilk", reports AP.