He was the son of the famous lithographer Jakob von Alt (1789-1872). He studied at the Akademie der bildenden Künste in Vienna. Hiking-trips through the Austrian Alps and northern Italy awoke a love in for landscapes, and he painted with his brush and using watercolors in a very realistic style. In 1833, inspired by a visit to Venice and neighbouring cities, he also made a number of architectural paintings. Alt demonstrated a remarkable talent for expressing certain peculiarities in nature. He managed to paint nature authentically by focusing on the different hues of sky, the colour-tone of the air, and the vegetation. His perspectives on architecture were interesting, and he often chose everyday objects to paint. The painting of interior-views also became one of his strong points, giving him attention in Vienna. He visited and worked for a while in Rome and Naples; after that he visited the lakes of Lombardy, then Bohemia, Bavaria and then returned multiple times to Italy. In 1863 he went to the Crimea to paint some views of an estate of the Empress, and in 1867 he went to Sicily. His younger brother Franz von Alt, (b. 1821 in Vienna) was also a painter.