Mohammed Seif al-Din Wanly was born into an aristocratic family of Turkish origin. He grew up with his four sisters and his younger brother, Adham, in an intellectual francophone environment. They were educated by private tutors in their family house, the Urfan Pacha Palace located in the neighborhood of Muharram Bey in Alexandria. Seif worked as a public official at the customs archives of Alexandria and started painting with his brother, Adham. In 1929, Ottorino Bicchi (1878 - 1949), an Italian painter from Livorno, opened a studio in Alexandria and the Wanly brothers were among his first students. After Bicchi left Egypt in 1934, Seif and Adham established their own studio in Alexandria
During the 1950's, the two brothers traveled regularly to Europe and visited France, Italy and Spain where they sketched and painted numerous scenes of ballet, opera and theater performances. When sculptor Ahmad Osman (1907 - 1970) established the Faculty of Fine Arts in Alexandria in 1957, Seif was appointed professor within the painting department. In 1959, the Ministry of Culture commissioned the Wanly brothers to record the architectural heritage of Nubia before its flooding due to the construction of the High Dam in Aswan. At the age of sixty-eight, he married the Egyptian painter Ihsan Mokhtar. He died in 1979 in Stockholm where he was preparing an exhibition of his Scandinavian landscapes.
The Wanly brothers were very close in their life and work. They influenced one another and developed a similar style. Seif only used his first name to sign his paintings while his brother, Adham, signed them by the name of Wanly or E. Wanly (Edham Wanly). Together, they introduced modern pictorial trends in Alexandria and were among the first to depict international subjects, breaking away from the folklorist style of their contemporaries.
Seif was a prolific artist who produced more than a thousand paintings, as well as numerous drawings and sketches. His early works are inspired by the use of the light and gentle strokes of his Italian professor, Ottorino Bicchi, who was close to the Italian Macchiaioli and the École de Barbizon. Later in his career, Seif used larger surfaces of bold colors and exercised greater freedom in his compositions, both of which brought him closer to Fauvism.
Seif was fascinated by the performance arts and depicted scenes of circus, ballet, opera, music concerts, bull-fighting as well as all types of sports, including horse races. His fascination with performance arts also led him to design several sets for theater and opera productions in Egypt. He painted numerous views of traditional Nubian villages before they were flooded, as well as many landscapes of Egypt and all the countries he visited, including Spain, France, Italy, Yugoslavia, Poland and Russia. Following the death of his brother, Adham, which affected him profoundly, he introduced a darker palette of colors and shades in his paintings. His works can be seen at the Seif and Adham Wanly Museum hosted in the villa of the Mahmoud Saïd Museum in Alexandria, the Museum of Fine Arts in Alexandria, the Museum of Egyptian Modern Art in Cairo, the Mathaf Arab Museum of Modern Art in Doha, as well as in numerous private collections around the world.