Valeška graduated from the Kaunas Art School in 1928. He then began work as a church decorator, moving on to co-found a museum of religious art in Kaunas. From 1939 to 1944 he served as director of the Vilnius Art Museum. During this period his work was exhibited in a number of venues, including the International Exhibition of Decorative Arts in Paris, 1935; the International Press Exhibition at the Vatican, 1935; and the International Exhibition of Decorative Arts in Berlin, 1937, where he earned a medal for designing the Lithuanian Pavilion.
Anticipating the Soviet occupation of Lithuania at the end of World War II, in 1944 he emigrated first to West Germany and then to the United States, where he established a studio in Chicago. He designed and executed a number of stained glass works and mosaics, as well as acting as stage designer for the Lithuanian Opera Company of Chicago.
Valeska's work includes:
Mosaics and stained glass at St. Philomena's Church in Chicago
