Bruce Adamson said legally allowing parents to smack their children puts Scotland at odds with the law in the majority of Europe.
Current legislation in Scotland enables parents to use a defence of justifiable assault for hitting their children.
Mr Adamson told the BBC’s Good Morning Scotland programme: “There are some things where Scotland is doing very, very well and there are some things that are absolutely shocking, where Scotland is coming last in the world.
“We really are coming last in this now. Almost every country in wider Europe is committed to this change and we still in Scotland say that it’s okay for a parent or carer to assault a child for the purpose of physical punishment, and that that can be justified, which is just untenable in international human rights terms.
“And I really think it really goes against the basic values that we hold in Scotland in terms of human dignity and respect for children.
“So it is a very strange position we are in, where the government isn’t supporting the change in the law at this stage, despite consistent international condemnation.”
He also criticised the current age of criminal responsibility in Scotland which is the lowest in Europe at eight.
He said: “At eight the idea that a child who is involved in behaviour that maybe harms someone else in quite a major way the idea that there is a criminal response to that, they should be held criminally responsible rather than their behaviour being addressed in a welfare-type model is idea is very very strange.
“The United Nations Committee on the Rights of the Child said 10 years ago that 12 was the absolute minimum and that anything below 12 was absolutely unacceptable internationally.”
Mr Adamson takes over the commissioner position from Tam Baillie, who campaigned for the Scottish Government to scrap the justifiable assault law.
Shortly before stepping down at the end of his term of office he said Scotland was lagging behind “pariah states” such as Zimbabwe by failing to ban smacking children and is one of only five countries in Europe where it remains legal.
The Scottish Parliament is holding a consultation on Green MSP’s John Finnie’s proposal to ban parents from smacking children.
The consultation closes in August, ahead of a planned Member’s Bill on changing the law.
The Scottish Government has repeatedly outlined its position that it does not support physical punishment of children but has no plans to outlaw smacking.
Minister for Childcare and Early Years, Mark McDonald, announced last year that the Scottish Government would bring forward legislation to raise the age of criminal responsibility to 12.