The discipline of Philosophy has always been widely encompassing inquiries from varied disciplines of both pure and social sciences; that is why now it includes almost every dimension of society. Pioneered in the Greek era, and evolved with the magnificent ancient historical foundations, Philosophy has gained worthy interdisciplinary vastness in 19th and 20th centuries. This thesis is an effort to explore Philosophy of cosmopolitan nationalism and its application in Sindh. This thesis discusses how the idea of nationalism has been critically evaluated as the world witnessed that the oppression under Hitler’s Nazism and Mussolini’s Fascism were also dubbed as nationalism. This damaged the justified and true nationalistic struggles of the beleaguered nations, of which Pakistan is the best example. This thesis is an effort to understand evolution of history, connotation and merits and demerits of cosmopolitan nationalism to comprehend the transformation of patriotic chronicles of Sindh’s political history into the precincts of cosmopolitan nationalism in Pakistan. Pakistan is a federation formed by the constituent units, in which the relationship between the units and the federation has always been estranged due to the thrust of the uniformity paradigm since the country’s inception, which cost division of the country in 1971. This thesis bases its main argument on Marxist perspective, which offers an enduring answer to the problems of Sindh by reforming its society with the help of class struggle as envisaged by Karl Marx and Fredrich Engels. The Marxist proposition of class struggle is judiciously used in the thesis; since Marx’s paradigm was universalistic, there is no doubt that in the present century cosmopolitan nationalism may take enormous benefit from Marxian paradigm in promoting class struggle to unite people of different ethnicities in Pakistan, as we observe this happening in the different parts of the world, particularly in the 20th century. The same can happen in Sindh as well. This especially is being done by some Marxist political activists in Pakistan, such as R. B. Palijo’s socialist paradigm in relation to Sindh province of Pakistan, to resolve tension between different ethnicities in the province of Sindh.