He went to Berlin as a youth to study Jewish theology, and there he became acquainted with Leopold Zunz and Abraham Geiger, the latter of whom was then staying in that city in order to become naturalized in Prussia.
Landshuth soon gave up his intention of becoming a rabbi, not being willing to conceal or renounce his liberal opinions; and Moritz Veit [de] aided him in establishing himself as a Hebrew bookseller.
His essay on the Haggadah (Berlin, 1855) and the introduction to Aaron Berechiah's Ma'abar Yabboq, a handbook of the funeral customs of the Jews, are along similar lines ("Vollständiges Gebet- und Andachtsbuch zum Gebrauche bei Kranken und Sterbenden," Berlin, 1867).
Landshuth's chief work was his "'Ammude ha'Abodah (Columnæ Cultus): Onomasticum Auctorum Hymnorum Hebræorum cum Notis Biographicis et Bibliographicis," on Hebrew liturgical poetry (2 vols., ib.
Landshuth also copied and arranged the early communal archives of Berlin (written in Hebrew) and the inscriptions of the old cemetery in that city, which was closed in 1827.