Depending on where and when the child was born, they may have been entitled to Canadian citizenship at birth. A child born abroad to a Canadian citizen parent is generally able to file for proof of that citizenship (see Derivative Citizenship). If your child was born after you obtained citizenship the process for immigrating them to Canada is similar to the Spousal Sponsorship.
The complication of these cases come when determining which section of the Canadian Citizenship Act apply to this particular client. The filing process for derivative citizenship can be completed and mailed to the appropriate office in Canada for processing. It is important to consult an experienced immigration professional to evaluate your unique situation and provide you with the best-case strategy.