He was born to Jean-Pierre Mazer († 1829), a silk weaver and stocking maker, originally from France, and his first wife, Brita Maria née Sjöman.
[1] He and his younger brother, Anton, went to a French convent school, where he studied music and Latin.
When their father died, he left them a large fortune, and they took over his company; Anton oversaw the manufacturing, and Johan the sales.
Their half-brother, Carl Peter, was studying art in Paris and never took part in the company's operations.
He was presented with a medal, inscribed with the Academy's motto: " Anda och Konst" (Spirit and Art).