He was the son of Johan Henrik Nebelong and Anna Christine Schreyber.

[2] In 1819 he was admitted to the Royal Danish Academy of Fine Arts where he studied under German-born, Danish architect Gustav Friedrich Hetsch and won both the small and large gold medal, in 1833 and 1837 respectively.

[1][3] After a few years as a teacher at the academy, he travelled to Paris, where he studied under Henri Labrouste, and then continued to Italy and Greece, before returning to Denmark in 1842.

He became a member of the academy in 1855 and the following year was appointed City Architect in Copenhagen.

Typically of the Historicist period, Nebelong worked in a number of different styles, including the late Neo-Classicism (Kolding Gymnasium, 1845–46), Gothic Revival (Slagelse Convent, 1857–59), and Romanesque Revival (Viborg Cathedral, 1863–76, completed by H.B.