[2] Johnson was born in Adelaide, the son of Henry Johnson, an Adelaide solicitor, by his marriage with Wilhelmina Colquhoun, née Campbell,[2] the third daughter of Colin Campbell, of Stonefield, Pine Forest, South Australia.
[3] His father moved to Victoria (Australia) during the gold-digging fever, Joseph was educated at the Geelong National Grammar School.
He conducted it for several years, but the paper suffered an irreparable loss when cartoonist W. J. Kennedy left.
[4] On 8 April 1884 Johnson was elected a member to the Electoral district of Onkaparinga in the South Australian House of Assembly,[5] and was Minister of Education and of the Northern Territory from 11 June 1887 to 27 June 1889[2][5] in the Thomas Playford II Ministry.
[3] Johnson was the author of "Moses and Me," the record of a visit paid to the Mount Brown diggings in 1880.