Frenssen studied theology and spent 10 years as a Lutheran pastor. His critical attitude toward orthodoxy, however, which later developed into a total rejection of Christianity, together with the resounding success of his third novel, Jörn Uhl (1901), led him to resign his pastorate and devote all his time to writing. Although Frenssen at times made liberal concessions to the popular taste of the moment, he owed his success, in large part, to the vitality of his characters and the charm and beauty he lent to the locale of his novels—the shores of the North Sea.

About half of Frenssen's novels were translated into English. Among them are: Die drei Getreuen (1898; The Three Comrades); Jörn Uhl (1901); Hilligenlei (1905; Holyland); Peter Moors Fahrt nach Südwest (1907; Peter Moor's Journey to Southwest Africa); Klaus Heinrich Baas (1909); Der Pastor von Poggsee (1921; The Pastor of Poggsee); and the autobiographical Otto Babendiek (1926; abridged, The Anvil).