Health minister Lesley Griffiths announced the changes on Tuesday following advice from experts.
GP broke the news in January 2012 that the UK National Screening Committee (NSC) was set to introduce a UK-wide cervical cancer screening policy.
The NSC had said evidence showed cervical screening was 'simply not effective in women under the age of 25'. It also advised that women over 50 should be invited every five years instead of every three.
The Wales Screening Committee has now backed the NSC's recommendations, meaning all four UK countries have a consistent screening age for cervical cancer.
Ms Griffiths said: 'Their recommendation to update the way we deliver cervical screening in Wales will bring the Welsh programme in line with current practice in England and Northern Ireland.'
Wales CMO Dr Ruth Hussey said: 'This is a positive service improvement for women. Any screening programme should ensure that the benefit of taking part outweighs the risks.
'Cervical cancer in women under 25 is extremely rare and usually picked up through the onset of symptoms rather than the screening programme. Latest evidence shows that most abnormal smear test results in this age group will clear up of their own accord. Therefore, screening women under the age of 25 may lead to a significant number of having unnecessary treatment and worry.'