Karim was born on 20 October 1919 and in the village of Klyashevo (now in Chishminsky District, Bashkortostan) in an ethnic Bashkir peasant family.

After graduation, he joined the Red Army and was sent to Novocherkassk Higher Military Command School of Communications.

In August 1942, Karim spent about six months in hospitals recuperating from severe wounds.

Throughout the Great Patriotic War Karim was at the front, and he was a correspondent for the front-line newspapers For the honor of the motherland (Ватан намусы өчен), Soviet Soldier (Sovet sugyshchysy) in Tatar.

Karim's contributions extended to being a member of the Presidential Council of the Republic of Bashkortostan.

He died after suffering a heart attack on 21 September 2005 at the Republican Cardiological Clinic in Ufa.

Collections of poetry and poems, "Black Water", "Return", "Europe-Asia", "time plays", "Country Ajgul", "The Kidnapping of Girl," "On the night of the lunar eclipse", "Salavat.

Works by Mustai Karim have been translated into dozens of languages of Russia and the world (Kyrgyz, Slovenian, Estonian etc.).