The actors have teamed up with the International Rescue Committee (IRC) as part of the 'Rescue Has No Boundaries' campaign, aimed at raising money for people displaced by conflict and natural disaster.
In a video released as part of the campaign, actress Lena Headey called out for people to "rise up" and donate money to the cause.
"Mass exodus, millions on the move escaping war, famine and destruction. This is no fiction, no fantasy," the cast say.
"Every month, hundreds of thousands flee their homes. Refugees. Families. Children. Struggling to stay alive. Real people, now on the most dangerous journey of all."
The pledge for more funding comes amid increased global attention of the plight of refugees, following conflict in the Middle East and Africa, which led to more than one million people claiming asylum in Europe in 2015 alone.
While the EU has accepted large numbers of refugees from conflict zones, efforts are being made to stem the flow of people entering Europe from the Middle East, sparking fears many people may be unable to leave war-torn countries.
The IRC campaign has been launched to coincide with the five-year anniversary of the Syrian civil war, which has been described by the UN as the "single biggest generator of both new refugees and continuing mass internal displacement."
The campaign is aiming to raise US$1 million in emergency aid for the crisis, with IRC chief David Miliband saying that he hopes the partnership with Game of Thrones actors can "galvanize the general public to take action and rise up for refugees."