The smoking ban in England for all enclosed public places and workplaces will begin on 1 July next year.
Announcing the date, Britain's Health Secretary Patricia Hewitt described the ban as a triumph for public health.
The smoking ban in Wales will start on 2 April. A smoking ban is already in force in Scotland.
The legislation was passed at Westminster last summer, not least because of the success of Ireland's smoking ban, but the British government decided to delay the introduction of its ban by several months.
In England more than 3.5 million businesses - including 200,000 pubs, bars and restaurants - will be affected.
Ms Hewitt said there was still a lot of work to do to get the country ready for the implementation of the new law.