Dhirubhai started his first textile mill at Naroda, near Ahmedabad in 1966 and started the brand "Vimal". Dhirubhai Ambani is credited with having started the equity cult in India. With the passage of time, Dhirubhai diversified into petrochemicals and sectors like telecommunications, information technology, energy, power, retail, textiles, infrastructure services, capital markets, and logistics.
Dhirubhai courted controversy all throughout his life. Many a times, he has been accused of unethical business practices and has been accused of having manipulated government policies to suit his own needs. He was involved in an open spat with Nusli Wadia of Bombay Dyeing. The end to this tussle came only after Dhirubhai Ambani suffered a stroke. While Dhirubhai Ambani was recovering in San Diego, his sons Mukesh Ambani and Anil Ambani managed the affairs. The Indian Express had turned the guns against Reliance and was directly blaming the government for not doing enough to penalize Reliance Industries. The battle between Wadia - Goenka and the Ambanis took a new direction and became a national crisis. Gurumurthy and another journalist, Mulgaokar consorted with President Giani Zail Singh and ghost-wrote a hostile letter to the Prime Minister on his behalf. The Indian Express published a draft of the President's letter as a scoop, not realizing that Zail Singh had made changes to the letter before sending it to Rajiv Gandhi. Ambani had won the battle at this point. Now, while the tussle was directly between the Prime Minister Rajiv Gandhi and Ramnath Goenka, Ambani made a quiet exit. The government then raided the Express guest house in Delhi's Sunder Nagar and found the original draft with corrections in Mulgaokar's handwriting. By 1988-89, Rajiv's government retaliated with a series of prosecutions against the Indian Express. Even then, Goenka retained his iconic stature because, to many people, he seemed to be replaying his heroic defiance during the Emergency regime.
Dhirubhai Ambani won many words and accolades during his life. In November 2000, he was conferred the 'Man of the Century' award by Chemtech Foundation and Chemical Engineering World for his contribution to the growth and development of the chemical industry in India. In June 1998, he was awarded the Dean's Medal by The Wharton School, University of Pennsylvania, for setting an outstanding example of leadership. Dhirubhai Ambani was also named the "Man of 20th Century" by the Federation of Indian Chambers of Commerce and Industry (FICCI).
Dhirubhai Ambani suffered a "brain stroke: on June 24, 2002 and was admitted to the Breach Candy Hospital in Mumbai. He had suffered another stroke in February 1986 which had paralyzed his right hand. He passed away on July 6, 2002. On Dhirubhai Ambani's first death anniversary, the Union Government released a postage stamp in his memory.