Paul Geissler studied drawing with the painter Sondermann and attended the Arts and Craft School in Erfurt for 4 years. In 1903, he studied at the Grand-Ducal School of Arts in Weimar, Germany, with Max Thedy. He received commissions for paintings from the German Empress and a Russian grand-duke. Subsequently, he gave up painting and specialized in etching, the art he liked best. Geissler worked on large etchings in Paris, 1910-11 and then moved to Munich, Germany in 1912. He served on the board of the Association for Original Etchings, in Munich. He traveled to Switzerland, Liechtenstein, Belgium, Holland, Austria, France, moving to Garmisch-Partenkirchen, Germany in 1918.

His most productive years were 1920-30. Geissler traveled to the US in 1928, returning home via Sicily and the Italian mainland.  In the US, he executed etchings of Independence Hall and the Betsy Ross House in Philadelphia as well as scenes of Yale and Princeton. Geissler was appointed professor in Germany in 1943 with several universities offering him a post, but he remained independent. He also served as Chairman of the Werdenfelser Kunstlerbund, association of artists in the Garmisch, Germany, area.