Gbagbo was arrested in April 2011 and transferred to the ICC to face charges of committing crimes against humanity in Ivory Coast from December 2010 to the time of his arrest.
The international community recognized Alassane Ouattara as the victor of 2010 election, meant to unite an Ivory Coast divided by war. At least 3,000 people died in the political violence that erupted after the election, Human Rights Watch reports.
Gbagbo's defense team challenged the admissibility of the case before the ICC in February. The ICC ruled Tuesday there wasn't a national case under way against Gbagbo.
"Therefore, according to the pretrial chamber, the case The Prosecutor vs. Laurent Gbagbo is still admissible before the ICC," a court statement said.
The U.S. State Department warned last month of the potential for violence in Ivory Coast. Ivorian forces are able to secure the peace but the warning said the security situation could quickly change.
Human Rights Watch said part of Ivorian recovery hinges on a credible investigation into the political issues that led to post-election violence. Both parties to the conflict are suspected of committing crimes against humanity.