Juncker was a student of the facade painter Hugo Schlegel (1679–1737) in Frankfurt am Main, who also worked with Christian Georg Schütz the Elder.

He was subsequently influenced by works of art in the collection of Baron von Haeckel. He worked in London for some time. In 1723 he moved to Frankfurt.

Juncker was one of the artists Johann Caspar Goethe employed to furnish his house in the Großer Hirschgraben. Juncker's students include his son Isaak Juncker, born in Frankfurt am Main in 1727, and his son-in-law Johann Daniel Bager, born in Wiesbaden in 1734.