"The United States will use all available tools to deny these branches of the Muslim Brotherhood the ability to practice or support terrorism," Secretary of State Marco Rubio wrote in a statement.
Egypt and other US allies in the region have long sought a terrorist designation for the organization.
The Sunni Muslim religious and political movement was formed in 1928 in Egypt and has since spread to a number of countries.
In 2012, the movement temporarily came to power in Egypt with the victory of Muhammad Morsi in the presidential election. However, Morsi was overthrown the following year in a military coup by Abd al-Fattah al-Sisi, who has since cracked down hard on the Muslim Brotherhood.
