[4] Prior to leading KPMG in India, Kumar served as Assistant Secretary of Commerce for Global Markets and director general of the US and Foreign Commercial Service (USFCS) in the administration of former U.S. President Barack Obama.

[6] With Kumar at helm KPMG in India is said to have focused on specific areas of growth – ranging from special situations to do with stressed assets to cyber security.

Kumar made sure that the Firm leverages on talent and skill availability in India to serve markets in proximate areas from Africa to East Asia.

[8] In his role as one of the top commercial diplomats of the United States, Kumar led the trade and investment promotion efforts for the U.S. Government responsible for a team of 1600 professionals located in over 100 U.S. cities and 78 world markets.

[10] In 2016, the Global Markets unit that he led served 28,692 U.S. exporters, mostly small and medium enterprises, assisted U.S. companies win over a hundred deals with foreign governments valued at $50.9 billion that supported about 178,000 American jobs.

[12] The S&CD placed commerce and business at the center of the U.S.-India relationship spawning bilateral engagement across a spectrum of activities: ease of doing business,[13] engagement in India's efforts to create a new bankruptcy code, encouraging new forms of financing including municipal bonds, co-operation in harmonizing standards, U.S. participation in smart cities development[14] and in the launch of the U.S.-India Innovation Forum.

[15][16] He was member of President Obama's delegation on his historic visit to India as the Chief Guest at the Republic Day celebrations in January 2015.

[17] Kumar oversaw the expansion and institutionalization of SelectUSA, the federal investment promotion initiative of the U.S. Government, that was housed in Global Markets.

[28] On July 25, 2014, Rep. Curt Clawson, a freshman Republican congressman from Florida, mistook Arun M. Kumar and Nisha Biswal (two senior U.S. officials) for representatives of the Indian government during a House hearing.

Peter Beinart contributing editor at The Atlantic termed the incident as silly gaffe that is revealing of our society where whiteness is still a proxy for being American.

[38] Kumar initiated, in 2009, the annual India Prospective discussion sponsored by KPMG and held at the Asia Society, New York after each Indian budget presentation to Parliament.

[50] Kumar has also contributed to the Huffington Post and has authored blogs on a range of topics including public service, American businesses, trade, commerce and global markets.