As "Small Business Saturday" becomes a worldwide phenomenon, lenders are becoming aware of the investment opportunities on Main Street, former Small Business Administration chief Karen Mills told CNBC on Friday.

Online technology companies including Amazon, PayPal and Square are now issuing near-instant loans to small businesses so they can bulk up their inventory ahead of the branded holiday, Mills said. Small Business Saturday, which began nine years ago, is sponsored by American Express.

"Technology has changed the game in small business lending," said Mills, who is now a senior fellow at Harvard Business School. "We're going to see things change completely."

"A small business preparing for Small Business Saturday can't wait three months to get an inventory loan," she told CNBC's "Squawk Box." "Now, they've got this sort of online loan within minutes."

Square Capital, a division of small-business-focused fintech Square, now makes loans of up to $100,000 to small shops, far outpacing what a traditional lender might provide in amount and speed.

Mills noted that even a loan of $7,000 would likely be considered fiscally imprudent for a bank, which she said wouldn't make any money from doling out a loan of that size to a smaller brick-and-mortar operation.

But "the J.P. Morgans of the world have woken up" to these challenges and are now "investing in a better customer experience," said Mills, who served was SBA administrator under former President Barack Obama.

"We are just at the opening of a huge transformation," Mills said as Black Friday ramped up across the country. "The world is going to change for small business for the better with technology."

In 2017, Small Business Saturday drove nearly $13 billion in consumer spending, down slightly from 2016. Small businesses account for about two-thirds of the new jobs created in the United States and half of the private-sector workforce.