Protestant theologian who worked for a unification of Lutherans and Calvinists.

Jablonski studied at Frankfurt an der Oder and at Oxford University and began preaching at Magdeburg in 1683. From 1686 to 1691 he headed the Moravian College at Lissa, becoming court preacher at Königsberg (now Kaliningrad, Russia) in 1691 and Berlin in 1693. In 1699 he was consecrated a bishop of the Moravian church.

While in Berlin, Jablonski unsuccessfully worked for the union of German, English, and Swiss Lutherans and Calvinists, winning the support of court circles and of the philosopher Gottfried Wilhelm von Leibniz (Leibniz, Gottfried Wilhelm). He also attempted to reform the church of Prussia by introducing the episcopate and liturgy of the Church of England but again was unsuccessful. He cofounded the Berlin Academy of Sciences, which he headed in 1733. Correspondence between Jablonski and Leibniz was published in 1747 and 1799.