The new rules, a result of the September 11 attacks on New York and Washington five years ago, apply to millions of travellers to the US each year. They were repeatedly delayed to agree on standards and give foreign governments time to adapt.
To keep visa-free privileges, countries will ensure that passports issued from October 26 onward have a chip storing the holder's biographic data and a biometric identifier, such as a digital photograph, the US Department of Homeland Security (DHS) said.
Meeting the deadline were 15 European Union countries, Japan, Australia, New Zealand, Norway, Singapore, Switzerland, Iceland, Monaco and San Marino.
Brunei, Liechtenstein and Andorra do not yet issue 'e-passports' and the US is working with them to make it happen, DHS said.
Until e-passports are available, travellers from the three countries will need a visa to enter the US if their passport is dated October 26, 2006 or later.
Electronic passports are 'a significant advance in preventing terrorists from using lost or stolen passports' to enter the US, Homeland Security Secretary Michael Chertoff said in a statement.
Electronic passports, which are run through readers by immigration officials at US borders, make it more difficult for criminals to travel on forged documents.
US officials have worked with countries in the so-called visa waiver programme for two years to agree on technical standards.
People from the 27 countries can still enter the US without a visa on older passports without a chip. If the passport was issued between Thursday and last October 26, it must have a machine-readable strip and a digital photo. Passports older than October 26, 2005 must be machine-readable.
The US visa waiver programme applies to business or private trips of 90 days or less. Some 15 million people a year travel to the US under the programme to conduct business, visit family or tour the country, DHS said.