The South Korean electronics giant launched an investigation into the Dongguan Shinyang Electronics Co. after the rights monitoring group China Labor Watch (CLW) reported the factory was employing workers under the age of 16.
"Following the investigation, Samsung decided to temporarily suspend business with the factory in question as it found evidence of suspected child labor at the worksite," the company said in a statement.
The Chinese authorities are also looking into the case, Samsung said, adding that if it was proved the factory hired children illegally the business suspension would become permanent.
The company stressed that it maintained a "zero-tolerance" policy on child labour and conducted regular inspections of its suppliers to ensure its implementation.
"It is unfortunate that the (CLW) allegation surfaced despite Samsung's efforts," it said, vowing to further strengthen monitoring to prevent similar cases in the future.
In its report, the New York-based watchdog had cited other violations at the same factory, including unpaid overtime wages, excessive overtime and a lack of social insurance and training.
Samsung said it had audited Dongguan Shinyang Electronics three times since 2013, including an inspection last month.
China Labor Watch called Samsung's monitoring system "ineffective".