In part to build this business, Nordheimer became one of the most active promoters of music in Canada. He brought prominent foreign stars to the city, such as Jenny Lind; opened a concert hall in Montreal, founded the Chamber Music Association, and for many years directed the Toronto Philharmonic Society.
A Bavarian immigrant, he lived first in New York City and then in Kingston, Ontario, before settling in Toronto in 1844. He and his older brother Abraham established a piano importing business, A.& S. Nordheimer Co.
The business prospered and expanded. It became Canada's leading publisher of sheet music, and initially had the sole right to publish copies of the Maple Leaf Forever. The company also opened branches in other cities across Canada. As well as continuing to import pianos, in 1890 the firm opened its own factory in Toronto and quickly became one of Canada's best known domestic piano brands.
Nordheimer became a prominent member of the city's commercial class, serving on a number of corporate boards. In 1871, the year married Edith Boulton, Nordheimer completed work on a massive home named Glenedyth. It was located on Davenport Hill, near James Austin's Spadina House. While the house was demolished in the 1920s, the ravine running by the site is still known as the Nordheimer Ravine.
Nordheimer remained head of the company until his death, when the firm was taken over by his nephew Albert. Upon his retirement from the business in 1928, the firm was taken over by Heintzman & Co. His legacy included a section of Castle Frank Brook being named after him.
In 1871 Nordheimer married Edith (1847–1912) — daughter of James Boulton and Margaret Neilina. They had a son and seven daughters.
Edith Nordheimer was from a prominent Toronto family that had played a leading role in the Family Compact and had built The Grange. She was an Anglican philanthropist and imperialist who became the first national president of the Imperial Order Daughters of the Empire (IODE) in 1901 and vice-president of the Toronto South African Memorial Association at the beginning in 1904 (the association established memorials for those who had fought in the South African War (1899–1902)).