Born in Vienna, Austria, Eisler studied architecture at the University of Vienna before fleeing the country in 1938 following the Anschluss, the annexation of Austria by Nazi Germany. He then moved to Argentina, where he worked for the modernist architect Jorge Ferrari Hardoy. In 1950, Eisler moved to São Paulo, Brazil, where he met Brazilian designer Greta Magnusson Grossman. Together, they founded the company Forma, which produced a wide variety of modernist furniture using materials such as metal and wood.
Eisler is best known for his collaborations with Brazilian designer Carlo Hauner, with whom he founded the company Móveis Artesanal da Ilha in 1953. Their work was characterized by organic forms inspired by nature and an innovative use of materials, such as hanging chairs made of cotton rope. They also worked for the Brazilian furniture and home accessories company, Forma.
Over the years, Eisler established his reputation as a versatile designer, working on a range of projects from furniture to upholstery to interior design. He also worked as an architect, designing modernist residential buildings.
Today, Eisler's work is exhibited in museums around the world, including the Museum of Modern Art in New York and the Museum of Contemporary Art in São Paulo.