The Department for Business, Enterprise & Regulatory Reform (BERR) says there are thousands of government contracts available.
The website provides a database of contracts for small businesses. Suppliers who sign up get advice on how to win contracts and a daily e-mail alert with new opportunities.
The government said the site was "refreshed" in November last year, providing a more "user-friendly platform" with more information and better navigation.
Business secretary of state Peter Mandelson said, "It is vital that we actively help small and medium sized companies take advantage of these business opportunities. In the current economic climate this is more important than ever. The supply2.gov.uk website is a crucial tool for this."