Jespers took up sculpture at the Royal Academy in Antwerp and opened his studio in 1912. He collaborated with friend and poet Paul van Ostaijen, producing Cubist illustrations for the only Dadaist poetry collection Bezette Stad. In 1924 his style moved away from Cubism to Expressionism. He settled in Brussels in 1929 and continued to work and exhibit for the following twenty years. In 1949 he moved to Maastricht and started teaching sculpture in addition to drawing.