Johan Christian Conradi (1709 – 30 September 1779) was a German–Danish master builder and architect.
Conradi was born in Gotha in the Sazon duchy of Saxe-Gotha. He moved to Denmark in 1739 where he was accepted into the masons' guild in 1740.
In the beginning of his career, Conradi worked as a mason and builder. His first major work as such was Ledreborg (1743–45). In the late 1740s he began routinely working for Niels Eigtved, architect to the Royal Court, executing projects such as the first Royal Danish Theatre at Kongens Nytorv (1748–49, demolished in 1874), Danish Asia Company's warehouse at Asiatisk Plads (1748–50), Christian's Church (1755-64) and the Lindencrone Mansion in Bredgade (1751). Later works include Almindeligt Hospital in Amaliegade which he completed to designs by Nicolas-Henri Jardin in 1760 (demolished in 1892) and maintenance work both on Kongens Bryghus and Børsen (1779).
From about 1750, Conradi increasingly also worked as an architect, designing the buildings that he built.
Many of Conradi's works are found in the Christianshavn neighbourhood. These include two houses at 50–52 Prinsessegade (1750), the Royal Bording School, now known as Søkvæsthuset (1753–55, later altered and expanded). the Wilder Warehouse at Wilders Plads (1762–63) and Royal Greenland's warehouse at Grøndlandske Handels Palds (now North Atlantic House. from 1764. His own house at Christianshavn Canal (29 Overgaden neden Vandet, 1752) and his rectory for Christian's Church have both been demolished.