The IMMAF confirmed it had approved the Guatemalan Association of Mixed Martial Arts (GUAMMA) and the Uzbekistan Mixed Martial Arts Association (UMMAA) as its newest members.
GUAMMA President Erick Schumann said becoming part of the IMMAF was a "big step forward in the development of Guatemalan sports".
The GUAMMA has served as the national governing body for mixed martial arts, representing affiliated academies from across the country, since 2011.
"For the first time, Guatemala is given the opportunity to participate in IMMAF tournaments within this discipline of martial arts," Schumann added.
"This is a big step forward for government recognition of mixed martial arts, the fastest growing sport worldwide, and it will expand the opportunities for its development in all areas of the country."
The UMMAA's acceptance as a member of the IMMAF comes just eight months after it was formed.
The organisation obtained legal recognition as the governing body for the sport in the country in October.
"Mixed martial arts is becoming a very popular sport in Uzbekistan," said UMMAA President Umarov Otabek Mukhammadalievich.
"Therefore, there was need for a national governing body to oversee its development.
"We plan to work closely with IMMAF to develop rules and regulations for the sport both nationally and internationally.
"We also look forward to fully representing Uzbekistan at an international level in IMMAF Amateur Championships.
"Hopefully one day our beloved sport will become Olympic sport and our athletes will have chance to show their skills to the world."