Born the son of a Jewish tailor in 1844 in Neustadt, Russian Empire, Marks was endowed with integrity, courage, astonishing business acumen and immense vitality. He accompanied some horses to Sheffield in England while still a youth and, not wanting to return to the Jewish persecution in Russia, decided to stay on. It was in Sheffield that he met his future in-laws. Hearing news of the diamond discoveries in Kimberley, he arrived at the Cape in 1869 and was shortly followed by his cousin Isaac Lewis, also from Neustadt-Sugind, with whom he forged the enduring partnership of Lewis & Marks. Marks started his career as a peddler in the rural districts of the Cape, but soon headed for Kimberley where his rise to prosperity began. They made a modest living supplying goods to mines and diggers, and later branched into diamond trading. Moving to Pretoria in 1881 he gained the confidence of President Kruger and the government of the Zuid-Afrikaansche Republiek (ZAR). His friendship with Kruger became close and enduring and they had in common humble origins and a ready wit. Marks advised that Kruger build a railway line from Pretoria to Lourenço Marques.With the discovery of gold in the boomtown of Barberton and later on the Witwatersrand, Marks acquired business interests in both places, but found the coalfields of the southern Transvaal and northern Free State to be a more lucrative prospect. The Zuid-Afrikaansche en Oranje Vrijstaatsche Mineralen en Mijnbouwvereeniging was founded in 1892 to mine these coal deposits, and later gave the town of Vereeniging its name. Lewis & Marks business interests included a distillery, a canning factory and a glass factory. Their firm opened collieries at Viljoensdrif and elsewhere, and also started Vereeniging Estates Ltd., which was dedicated to developing agricultural land along the Vaal River. Marks pioneered the use of steam tractors and progressive farming implements. He also sponsored the establishing of flour-mills and brick and tile works at Vereeniging. In 1910 Marks was nominated as senator in the first Union Parliament, an office he held until his death. When A.H. Nellmapius was unable to execute a manufacturing contract he had concluded with the Government due to lack of funds, Lewis & Marks took over and constructed the Eerste Fabrieken near Pretoria.
Marks contributed generously to Jewish communities all over South Africa. The Pretoria synagogue was built in 1898, for which he donated all the bricks and paid for the electric light installation and chandeliers. At the end of the Anglo-Boer War, he presented a cast-iron fountain to the city of Pretoria, shipped from Glasgow and very Edwardian in design, it stands at the Zoological Gardens in Pretoria. Marks commissioned the statue of Kruger on Church Square in Pretoria – sculpted by Anton van Wouw and cast in bronze in Europe, it carried a price tag of £10,000.