Aleksey Vasilyevich Mozaev was born on October 5, 1918, in the village of Vtoraya Sosnovka, Saratov Province, in a family of teachers.

In 1933 and 1936, he studied at the Penza Art and Pedagogical College under N. F. Petrov and I. S. Goryushkin-Sorokopudov. In 1936, at the invitation of I. I. Brodsky, Mozaev moved to Leningrad and successfully enrolled in the Leningrad Institute of Painting, Sculpture, and Architecture in the painting department. His mentors included Mikhail Bernstein, Alexander Lyubimov, Isaac Brodsky, and Heinrich Pavlovsky.

In 1941 and 1942, he worked in Saratov at "Okna TASS." In 1943, he returned to his studies in the workshops of Alexander Osmyorkin and Boris Ioganson. In 1946, he graduated from the Leningrad Institute of Painting, Sculpture, and Architecture named after I. E. Repin under the guidance of Boris Ioganson, presenting his diploma painting "In the Native Family." In the same year, he became a member of the Leningrad Union of Soviet Artists and the Artists' Society of Lenizdat.

Mozaev's first exhibition participation took place in 1936. From the late 1940s, he regularly participated in exhibitions of Leningrad artists. He created portraits, landscapes, and genre compositions, working in oil painting, drawing, and autolithography. Mozaev was a talented draftsman and held solo exhibitions in Leningrad and St. Petersburg.

The main genre of Mozaev's work was the painted portrait. His style evolved from an academic manner with an emphasis on objectivity and typification to a more expressive reflection of individual traits and refined color. Mozaev's paintings were characterized by bright light and shadow contrasts and skillful transmission of plein air. Over time, the decorative quality of his color and the generalization of his drawing intensified. In 1989 and 1992, his works were successfully exhibited at exhibitions and auctions of Russian painting L' Ecole de Leningrad in France.

Aleksey Mozaev spent over 30 years in pedagogical activities at the Secondary Art School, now the St. Petersburg State Academic Art Lyceum named after B. V. Ioganson, at the Leningrad Institute of Painting, Sculpture, and Architecture named after I. E. Repin, and at the Leningrad Art College named after V. A. Serov, now the St. Petersburg Art College named after N. K. Rerikh.

He passed away on January 23, 1994, in St. Petersburg at the age of 76 and was buried at the Kazan Cemetery in Pushkin.

Works by A. V. Mozaev are held in museums and private collections in Russia, France, the USA, the UK, Japan, Italy, and other countries.