Professionals will face action if they do not alert the relevant local authority under the law passed in May.
They will be given the right to enter premises to check if a vulnerable adult is making their own decisions.
Social Services Minister Mark Drakeford said the measures would protect those who are most at risk.
Among those affected by the new law are probation service providers, local health boards, NHS trusts, youth offending teams and the police.
People who fail to report incidents of abuse under the new legislation could face disciplinary proceedings or action for breaching their professional code of conduct.
Currently, there is no statutory duty on agencies to report suspected child abuse to social services.
"We're not proposing to create a new criminal offence but people would be liable to sanctions through their own professional and disciplinary procedures," Mr Drakeford.
"We will certainly be providing guidance on the way that new duties should be operated."
Suspected risk of abuse or neglect of children or adults must reported by police, health staff and other workers from 2016, it has been confirmed.