Hans Ernst Homberger was born in Schaffhausen on 31 October 1908, the son of Ernst Jakob Homberger, head of the Georg Fischer engineering company from 1902, and of Bertha Margaretha Rauschenbach, granddaughter of the man who had bought the International Watch Company in 1880. His father became sole owner of IWC from 1929, buying out the share of his brother-in-law Carl Gustav Jung.
Before he joined the business he was an international rower. With his brothers Rudolf and Alexander he rowed for the Ruderclub Zürich. At the 1935 European Championships in Berlin he won gold in the coxless four and silver in the eight with both brothers, and at the 1936 Berlin Olympics, on 14 August, he won silver in the coxed four and bronze in the coxless four; later that day the exhausted Swiss crew, including the Hombergers, finished sixth in the eight, for which they had been favourites.
He joined his father's company in 1934 and took over as managing director and sole proprietor when his father died in April 1955, the third generation of the Rauschenbach family line and the last to own IWC. The first Ingenieur (Ref. 666) appeared that year. In 1957 he added a new factory wing and a modern staff pension fund, and he kept investing in production machinery. After the gold-price and currency shocks of the mid-1970s, his directors Otto Heller and Hannes Pantli steered IWC into pocket watches and Porsche Design watches. In 1978 he sold a majority stake to the German instrument maker VDO Adolf Schindling, ending family ownership. He died in Schaffhausen on 26 January 1986, aged 77.