The court said four individuals under its protection were abused sexually by a former staff member working in the country.
"The review team is mandated to establish all facts and circumstances surrounding the allegations of sexual crimes against the four individuals and to identify all responsible persons, including those responsible for exercising managerial oversight over the suspected perpetrator," the court said in a statement Thursday.
The court said it made the decision to start a third-party review after completing an internal audit. The court did not provide specifics.
The ICC is investigating a series of human rights abuses and war crimes charges in DRC. The country is struggling to ensure national stability in the wake of a rebel campaign waged by the militant March 23 Movement.
M23 is suspected of conscripting child soldiers and using rape as a weapon of war.
M23 leader Bosco Ntaganda surrendered to the ICC in March to face charges of committing crimes against humanity.