Yossi Stern was born in the village of Kajar, Hungary. In 1939 he immigrated to Israel on the illegal immigrant ship Skeria, but was sent to a detention camp in Atlit. In 1943, he began his studies at Bezalel. At the same time, he made a living as a youth counselor in the Bukharan neighborhood of Jerusalem. During the War of Independence he joined the Haganah, where he was part of the organization's "Hamagen" newspaper in Jerusalem.
After the establishment of the State of Israel, he traveled to London, England, to study art with the help of a scholarship received by the Israeli government.
In the second half of the 1940s Stern created expressive drawings and paintings, influenced by the work of Jacob Steinhardt. Stern also developed a career as an illustrator and caricaturist. Later, Stern changed his style and began to create drawings with folkloristic motifs, including descriptions of Jerusalem,