He was born in the rectory of Lichtenau in southern Greenland (present-day Alluitsoq) to a couple of Moravian missionaries, Johann Konrad Kleinschmidt (1768–1832) from Oberdorla in Thuringia, Germany and Christina Petersen (1780–1853) from Trudsø, now a part of Struer, Denmark.
As a youth, he went to school in Kleinwelke, Saxony in Germany and subsequently for an apprenticeship to a pharmacy in Zeist, Holland studying during that period Latin, Greek, and Hebrew, as well as Dutch, French, and English, all the while retaining his childhood languages, Danish, German, and Greenlandic.
After two years he held his first sermon in Greenlandic, speaking it fluently and plainly rather than using old worn-out idioms of the previous ministers.
From 1846 to 1848 he worked as a teacher in Lichtenfels (present-day Akunnat), subsequently moving to Neu-Herrnhut (Old Nuuk).
He died in 1886 at 72 years of age in Neu-Herrnhut (present-day Noorliit, a part of Nuuk), having spent 54 of them in Greenland.