In 1844 he earned his doctorate from the University of Marburg, where he was a student of Orientalist Hermann Hupfeld (1796–1866). From 1845 he served as a pastor at St. Martin Church in Kassel. In 1850 he became an associate professor of theology at Marburg, where he attained full professorship in 1864.
Heppe specialized in the field of dogmatics, and excelled in the study of Hessian church history. At Marburg, he was a prime antagonist to the strict Confessional Lutheranism that was espoused by professor August Friedrich Christian Vilmar (1800–1868).
Among his published works was an 1861 textbook, titled Reformierte Dogmatik that was later translated into English and published as "Reformed Dogmatics". Other noted works by Heppe include:
- Geschichte der Hessischen Generalsynoden von 1568-1582 (History of the Hessian general synods of 1568-1582), vol. 1, vol. 2; 1847.
- Die Restauration des Katholizismus in Fulda, auf dem Eichsfelde und in Würzburg (The restoration of Catholicism in Fulda, Eichsfeld and Würzburg), 1850.
- Dogmatik des deutschen Protestantismus im sechzehnten Jahrhundert (Dogmatics of German Protestantism in the sixteenth century), 1861.
- Geschichte des deutschen Protestantismus, vol. 1; vol. 3; vol. 4; (History of German Protestantism), 1859.
- The Reformers of England and Germany in the sixteenth century, 1859.
- Geschichte des deutschen Volksschulwesens (History of the German people's education), 1858–60.
- Schriften zur Reformierten Theologie, (Wrtings of the Reformed movement's theology), 1860.
- Theodor Beza: Leben und ausgewählte Schriften, (Theodor Beza: Life and selected writings), 1861.
- Die Dogmatik der evangelisch-reformierten Kirche, (Dogmatics of the Evangelical Reformed Church), 1861.
- Geschichte der quietistischen Mystik in der katholischen Kirche (History of Quietistic mysticism in the Catholic Church), 1875.
- Geschichte des Pietismus und der Mystik in der reformierten Kirche (History of Pietism and mysticism in the Reformed Church), 1879.
- Friedrich Wilhelm Bautz (1990). "Heppe, Heinrich". In Bautz, Friedrich Wilhelm. Biographisch-Bibliographisches Kirchenlexikon (BBKL) (in German) 2. Hamm: Bautz. cols. 726–727. ISBN 3-88309-032-8. English translation
- Ernst Bizer (1969), "Neue Deutsche Biographie (NDB) (in German) 8, Berlin: Duncker & Humblot, pp. 570–570",
- Works by Heinrich Heppe at Project Gutenberg
- Works by or about Heinrich Heppe at Internet Archive (search optimized for the non-Beta site)