Small Business Saturday is in its third year, and aims to encourage people to spend locally rather than with international chains.
There are around five million small firms in the UK which employ half of the country's workforce.
The government said it wanted to help "cut red tape" for small businesses.
Business Secretary Sajid Javid said: "Small Business Saturday is an opportunity to come together and generate a real boost for small firms in the run-up to Christmas.
"Having grown up above the family shop myself, I'm proud of the UK's small businesses, providing jobs and security for millions of people and making a huge contribution to our economy."
Any firm with fewer than 50 employees is considered a small business.  In Britain 99% of all companies are in that category - employing 12.4 million people.
Last year UK traders took Â£504m on the day from an estimated 16.5 million people - a 20% increase in footfall on 2013.
But day-to-day small firms face a battle competing with big companies who can offer lower prices and have more resources to deal with issues such as administration, tax and staffing.
The Federation of Small businesses said that for every pound spent at an independent company,  around 70p stays in the local economy.
Shoppers across the UK are being encouraged to buy from independent stores on Saturday as part of a campaign to boost high streets.