More than half of all the imprisoned reporters, bloggers, and editors in the world are in those three countries, the CPJ said.
Azerbaijan and Uzbekistan also made the top 10 list of countries with jailed journalists.
It is the second consecutive year that Turkey and Iran topped the CPJ's list.
The CPJ says there are currently 40 journalists in Turkish prisons who are jailed for their work, down from 61 in October 2012.
In Iran, the number of jailed journalists is 35, down from 45 one year ago.
The remaining list of top 10 countries for jailing journalists is, in order: Eritrea, Vietnam, Syria, Azerbaijan, Ethiopia, Egypt, and Uzbekistan.