Jørgen Christian Knudsen was born to Christen and Guro Knudsen. The family bought the farm Frednes in Eidanger in 1854, and moved there. Jørgen Christian Knudsen had one sister Elen Serine, who married Johan Jeremiassen, and one brother Gunnar. Gunnar Knudsen would later become Prime Minister of Norway.
In 1867 Jørgen Christian Knudsen married Marie Henriette Resch, daughter of captain Hagbarth Resch. They settled at Frednes farm.
He was mayor of Porsgrund municipality in 1893, and vice mayor in 1891, 1892, 1894 and 1895. He was elected to the city council for the first time in 1877. He also represented the city in the Norwegian Parliament.