He was a student at the Thomasschule zu Leipzig and University of Leipzig, then organist of the city's Paulinerkirche from 1716 (whose music director he became in 1723) then its Nikolaikirche from 1721.
From 1907 he worked in Leipzig, where he was music director of the university until 1908 and professor of composition at the conservatory until his death.
Around 1610, he became cantor at the university church Paulinerkirche, which was famous for its substantial musical performances at both religious and academic events.
For the memorial service for Ernesti's death held on 21 October 1729 in the Paulinerkirche, the university church, Bach composed the motet Der Geist hilft unser Schwachheit auf, BWV 226.