The change was one of several amendments to exclusion procedures which the Welsh Assembly approved this week. The proposal to give 11 to 18-year-olds, as well as their parents, the chance to appeal against exclusions had originally been put forward by Peter Clarke, the children's commissioner for Wales.
The commissioner had also recommended placing a "mature young person" from another school on each exclusion appeals panel. But Welsh education officials dropped this proposal because of concerns that students on these panels might face bullying and intimidation.
Teaching unions applauded several of the changes to exclusions, which come into effect on January 9. Exclusions in Wales will no longer be overturned because of minor procedural errors - a change made in England last year.
However, unions remain concerned about allowing pupils to launch their own appeals.
Anne Hovey, regional officer for the National Association of Head Teachers in Wales, said heads believed pupils would be tempted to appeal in cases that parents would recognise were lost causes. "It is going to add unnecessarily to what is already quite a bureaucratic process," she said.
Dr Heledd Hayes, education officer for the National Union of Teachers Cymru, said: "We do not believe that decisions and responsibilities that belong to professionals and to other adults such as parents should be placed on a young person. To do so would be a dereliction of care."
The Advisory Centre for Education, a charity which provides support for families, approved of the changes.
Alison Murdoch, an adviser with ACE, said the impact of the Welsh children's commissioner on the regulations gave hope that England's planned children's commissioner would also succeed in giving young people a greater voice on such issues as exclusions.
A Welsh Assembly spokeswoman said that the number of appeals might increase because of the new powers for pupils, but that other changes would reduce the bureaucratic burden on schools.
"We feel it is important, wherever possible, for young people to be able to participate in processes which affect their education and life," she added.