Emrah Erdogan, who officials said is between 25 and 30 years old, recruited fighters and raised funds for Al-Qaeda and for Somalia's Al-Shebab groups, according to the US State Department, which also blamed him for attacks in Kenya and Uganda.
Captured in Tanzania, Erdogan was extradited to Germany, where he was tried and convicted in January 2014 for joining militant groups in Pakistan and Somalia and phoning in a false threat of attacks in Pakistan and Germany in November 2010.
The married father of two is currently serving a seven-year prison sentence in Germany, the US statement said.
Inclusion on Washington's terror list "imposes sanctions on foreign persons that have committed, or pose a serious risk of committing, acts of terrorism that threaten the security of US nationals or the national security, foreign policy, or economy of the United States," the State Department said.
The terror designation allows the United States to block any property or assets in which Erdogan "has any interest" and bars US citizens from engaging in transactions with him.
Erdogan's name also has been added to a UN sanctions list "requiring all member states to implement an assets freeze, a travel ban, and an arms embargo" against him, the State Department said.