Jamjoom is a founder and board member of Jamjoom Pharmaceuticals Factory, one of Saudi Arabia's largest producers of over-the-counter medicines. He owns a nearly 42% stake in the company, which is based in Jeddah and went public on the Saudi stock exchange in 2023. His son Mahmoud is the chairman of the company. From 1965 to 2005, Jamjoom was also the CEO of Jamjoom Medicine Store, which specialized in storing and distributing pharmaceutical products.