He founded Dynamic Sales Service International, a commodities trading and marketing company, which further expanded into railways, infrastructure, shipbroking and additional industries.

[26] During his service in the army, Khanna was part of the Indian contingent of the United Nations Emergency Force (UNEF), which was formed in the aftermath of the Suez Crisis, and was deployed to Egypt.

[27] During his travels, Khanna established connections with various individuals, which later contributed to the development of his international network in his business career.

[10] Khanna stated that his reasons for seeking premature retirement were that he saw no future prospects for himself within the army and that he had domestic concerns.

He began his career by joining Delhi Small Scale Industries, a textile manufacturing and import-export company founded in the 1950s by his father, Shanti Lal.

[30] In 1967, Khanna and Vinod were involved in the Lok Sabha's Committee of Privileges inquiry due to allegations of using improper influence and misleading officials in business dealings related to the import of sulfur by Amarjyothi.

[30] However, in 1969, the Committee of Privileges found insufficient evidence to substantiate the allegations of misconduct or improper influence against both brothers, and concluded that Amarjyothi's business dealings were conducted legally and did not breach any regulations or ethical standards.

[31] In 1967, Khanna founded Dynamic Sales Service International (DSSI), which initially started as a commodities trading and marketing company.

[36][37] According to the communication documents from Khanna to the US Department of State, these included connections with then-Prime Minister Indira Gandhi, members of various cabinet committees, and the executives of public sector undertakings (PSUs).

[45] DSSI's engineering support division collaborated with HMT to establish Indian Railways' first wheel and axle factory, developed the Oil & Natural Gas Corporation's first subsea production system in collaboration with Engineers India, and set up power plants for National Fertilizer's Bhatinda and Panipat facilities as well.

[47] DSSI Exports entered the fast-moving consumer goods (FMCG) industry and launched Chelsea, which was a tea brand.

[56] In 1997, Khanna entered the drinks and alcohol industries through his company Clan Morgan, which was based in Alwar, Rajasthan.

[68][70] Khanna and Aditya also opened Imli, an Indian restaurant in Soho, London, which was rebranded as Tamarind Kitchen in 2017.

[78][79] During his tenure as Honorary Consul, Khanna supported the idea that India would benefit if Luxembourg established banks in the country.

[14][15] In 2012, the Enforcment Directorate (ED) claimed that Khanna and his family's network in the Indian defence industry grew more powerful after the Bofors Scandal.

[13] In 1986, officials from the Ministry of Finance conducted an investigation into Khanna for allegedly being an arms agent for Saab, a Swedish defence and aerospace company.

[55] In 1999, it was alleged that Khanna was the arms agent for Thomson-CSF, a French defence, aerospace and electronics company that was rebranded as Thales Group in 2000.

[88][89] Berry claimed that Khanna was allegedly the arms agent for several Israeli defence companies, among which were Elbit Systems, Elisra, Tadiran Communications and Symtech.

[89] In 2024, it was reported that in 2005, Embraer, a Brazilian aerospace manufacturer, had an agreement with a UK-based company stipulating that Khanna would receive a 9% commission on the total value of defence contracts secured from the Indian Air Force (IAF).

[86][87] In 2005, Khanna was accused for allegedly facilitating the arms deal that involved the sale of 1,200 anti-material rifles from Denel, a South African aerospace and defence company, to the Indian Army.

[91] The CBI and the ED claimed that Khanna allegedly used Varas Associates, an offshore company with offices in the Isle of Man and Berne, Switzerland, to receive a commission of 12.75% for securing the order for Denel.

[98] In 2016, the CBI launched a probe into the purchase of three airborne early warning and control (AEW&C) aircraft from Embraer.

[99][100] Khanna was accused of swinging the aircraft deal, which was signed in 2008, in favour of Embraer by influencing the IAF and the Defence Research Development Organization (DRDO).

[101][102][103] The first information report (FIR) filed by the CBI mentioned that Khanna used an offshore company named Interdev Aviation Services Pte Ltd, located in Singapore, to channel payments from Embraer into India to use for kickbacks.

[108] Reportedly, Natwar Singh, the then-Minister of External Affairs and a family relative of Khanna's, received kickbacks, parts of which allegedly went to Saddam Hussein's regime in Iraq.

[109] It was also reported that Natwar Singh allegedly helped procure oil contracts for some companies owned by Khanna and his son, Aditya.

[111][110][112] Between 2006 and 2007, Khanna was connected by the CBI and ED to a network of offshore companies based in London, the Channel Islands and the Isle of Man.

[113][114] Khanna denied any links to all offshore companies and financial transactions, and Gopal Subramaniam, an Additional Solicitor General of India, stated to the Supreme Court of India that both the CBI and the ED had found no material evidence linking Khanna to offshore companies and the transactions.

[12] It was also reported that Khanna's son, Aditya, and his company, DSSI, were hired by Securency to assist in circulating its polymer banknotes in India.

[23] Through another of her sisters, Kailash Kumari Devi, Naginder was the sister-in-law of Rajendra Narayan Singh Deo, former Chief Minister of Odisha.