Citizens Advice (previously Citizens Advice Bureau and also known as Cyngor ar Bopeth in Welsh) is an independent organisation specialising in confidential information and advice to assist people with legal, debt, consumer, housing and other problems in the United Kingdom.

The twin aims of the Citizens Advice service are "to provide the advice people need for the problems they face" and secondly "to improve the policies and principles that affect people's lives". This research and campaigns agenda also known as "social policy" is more preventative in nature and designed to stop problems arising in the first place.

Citizens Advice organisations emerged in the 1930s linked to the emergence of a fledgling social welfare service and the outbreak of World War II. Public funding for the organisation was cut following the war but restored during the 1960s and a government grant in 1973 allowed the National Association of Citizens Advice Bureaux (NACAB) to expand the charity. Citizens Advice has grown to be the largest independent advice provider in the United Kingdom. There are also a number of Citizens Advice organisations that base themselves on the United Kingdom advice charity mainly in parts of the Commonwealth including Australia, New Zealand, and Gibraltar.

In 2013 the Citizens Advice Adviceguide website was visited by one third of United Kingdom's online population and Citizens Advice's own research shows that four in ten of the British population contact Citizens Advice at some point during their lives. In 2014 Citizens Advice celebrated its 75th anniversary and in 2015 the charity was named Charity of the Year at the 2015 Charity Awards. During the ten year leadership of the former Chief Executive Gillian Guy Citizens Advice expanded its remit taking on the contract for the Witness Service and the face-to-face advice element of Pension Wise.