It is the second part of the UK to do so after Scotland passed a ban last year.
In a landmark vote, Welsh Assembly members voted 36 to 14 to approve the Children (Abolition of Defence of Reasonable Punishment) (Wales) Bill.
Behind the Bill is the deputy minister for health and social services Julie Morgan, a long-time campaigner for children’s rights and an end to the physical punishment of children.
The new law in Wales is expected to come into force in 2022 and will be accompanied by an awareness campaign to inform the public about the changes.
Deputy minister for health and social services, Julie Morgan said, ‘Physical punishment has no place here in Wales – there is no such thing as a loving smack and no justifiable reason for a big person to hit a little person. I’m delighted we have voted to change the law to help protect our children and future generations.
‘I have longed campaigned for this change in the law and want to thank all those who have supported this legislation over the years.
‘The change in law will bring clarity for parents, professionals and children that physically punishing a child is not acceptable in Wales.’
First Minster Mark Drakeford, added, ‘I’m proud Wales has taken this step and once again put children’s rights at the heart of what we do.
‘Protecting children and giving them the best start in life should always be our priority.
‘Times have changed and there is no place in a modern society for the physical punishment of children. Wales joins Scotland in being the first parts of the UK to see through a positive change to this key piece of legislation.’
The Association of Educational Psychologists (AEP) congratulated the Welsh Government on the passing of the Bill and called on the Prime Minister Boris Johnson to follow suit, as well as discuss the move with the new devolved government in Northern Ireland.
General secretary Kate Fallon said, ‘Educational psychologists have believed for many years that the physical punishment of children is detrimental to their physical and mental wellbeing.
‘There are many other more effective ways of teaching children right from wrong than by hitting them.
‘We congratulate the Welsh Assembly and Scottish Parliament for introducing bans and we now call on the Prime Minister to bring forward a ban in England, and to discuss with the new devolved government in Northern Ireland, so that there is a UK wide end to the defence of reasonable punishment.
‘Sixty countries already have full bans on smacking, including Sweden, Ireland, Spain, Germany and Portugal, and it is time to make violence against children illegal in all parts of the UK.’