Children commit crimes and they are convicted daily in our courts. Once the court convicts the child as an offender, it must impose correctional measures immediately. The major rationale for handling down the child to correctional mechanisms is to rehabilitate the child offender. Thus, the Juvenile Court is obliged to maintain and strengthen family relationships, choose a least restrictive sentence which is proportionate to both offence and offender that makes a child offender change and accept his or her responsibilities towards the commission of the offence. The obligation of the juvenile court is well enshrined in international legal instruments which necessitated the introduction of the key principles to be considered in sentencing child offenders in Tanzania. The key principles introduced by the international instruments focus on: rehabilitation of the child offender; maintaining and strengthening family relationships; being least restrictive; be proportionate to the youthfulness of the child; consideration of the interest of the society; and enabling the offender to accept responsibilities over the offence committed. Based on this, the Child Act focuses more on non-custodial sentences; the key principles to consider when sentencing the child are not provided in the Act explicitly rather there presented in its Rules. The present article discusses Case Laws, Statutes provisions and international laws and the legal position in Tanzania regarding the key principles and substances to consider when sentencing a child offender. It further points out the gaps of laws and practices which normally emerge when considering proper sentence to a child offender. It is concluded that laws regarding sentencing child offenders should reflect the international instruments. The courts and other state organs should make sure their practice meets the purpose of sentencing children offenders.