This dissertation is a history of the Omani Empire focused primarily on the first half of the nineteenth century. I use the reign of Oman's longest serving ruler, Saʿid bin Sultan (1804/6-1856), as a lens for highlighting the formative role the Omani Empire played in uniting the Atlantic and Indian Oceans into a shared oceanic marketplace, a crucial step in the emergence of modern global capitalism. It is based on archival research and published primary sources from throughout Oman, Zanzibar, India, France, the United Kingdom, and the United States. This work reveals the Omani Empire as a new, mostly overlooked space for seeing how entrepreneurs and statesmen combined imperial agendas, slave labor, and the singular pursuit of profit in uniting disparate markets into global circuits of exchange. Across six chapters, I unravel the process by which Zanzibar, the empire's capital, became a monied metropolis bursting with entrepreneurs from throughout the world, trading in the most coveted consumer goods of the time. By using an oceanic framework, I bring into focus an entire history of empire and capitalism that has been largely overlooked by many Middle East and Islamic world historians because of a conventional adherence to terrestrial units of analysis. Most broadly, I aim to show how the makings of the modern world lie as much in places like East Africa and the Arabian Peninsula as in places like England or New England. Accordingly, I use the Omani Empire as a platform for arguing that the formation of global capitalism resulted from relatively new maritime markets throughout the Atlantic Ocean being incorporated into the longer standing Indian Ocean world.