The Prime Minister called for a new era of cooperation between the UK and India as he led a delegation of British ministers and business executives to Bangalore and, later, New Delhi.
Appealing for deeper trade ties that would fuel jobs back home, he also sought to demonstrate that India stood to gain from a closer relationship with Britain.
His visit coincided with the announcement that, in future, export licences for civil nuclear expertise and technology to India would be approved.
Whitehall has traditionally vetoed such cooperation because India has not signed the Nuclear Non-Proliferation Treaty or separated out its civil and military programmes.
The move will not only please the Indians but UK firms involved in nuclear research, like Rolls-Royce and Serco, stand to benefit too.
Mr Cameron also sought to address Indian concerns about terrorism, particularly from its neighbour Pakistan.
Video: PM's charm offensive for India
In forthright comments that angered Islamabad, the Prime Minister warned that Pakistan must not be allowed to "promote the export of terror" to the world.
He said he would be raising the issue with the Indian prime minister Manmohan Singh when they hold talks in Delhi tomorrow.
Mr Cameron's spokeswoman insisted he was talking about Pakistan as a country, not its government.
But in a later interview, he said: "It is an issue where we have to make sure that the Pakistani authorities are not looking two ways."
He described India, by contrast, as "responsible" and backed calls for it to be awarded a seat on the United Nations Security Council.
A new agreement between BAE Systems, Rolls-Royce and Indian aerospace company Hindustan Aeronautics Limited (HAL), to provide India with 57 more Hawk jets, was also announced.
Visiting HAL's Hawk facility in Bangalore, Mr Cameron hailed the £700 million deal as an "outstanding example of India-UK defence and industrial partnership".
Areas where further cooperation was needed included defence technology, counter-terrorism and climate change, he said.
The two countries are to help each other in terms of policing and security at the 2010 Commonwealth Games and 2012 Olympics that India and the UK are respectively hosting.
There were even reports in the Indian press - unconfirmed by British sources - that the Royal Navy and its Indian counterpart were embarking on submarine war games off the coast of Goa.
The Prime Minister said he wanted to make the UK "the partner of choice" for India.
But he also struck a humble note and acknowledged that Britain was one of many suitors that India now had.
In a sign of the radical shift in relations between the two countries since the days of empire, he wrote in a newspaper article for The Hindu: "I have come to your country in a spirit of humility.
"I know that Britain cannot rely on sentiment and shared history for a place in India's future.
"Your country has the whole world beating a path to its door. But I believe Britain should be India's partner of choice in the years ahead.
"Starting this week, that is what we are determined to deliver."
In a speech at the Bangalore base of global IT firm Infosys, the Prime Minister acknowledged that he was on a "jobs mission" to the sub-continent.
But he added that there was much to be had for India in a "new relationship" with the UK.
He pointed to Indian involvement in UK car manufacturing and steel production and called on India in turn to reduce trade barriers in banking, insurance, defence manufacturing and legal services.
He went on that 90,000 people were employed in the UK by Indian firms, and "many more" because of the activities of British firms in India.
"Now I want to see thousands more jobs created in Britain, and of course thousands more in India through trade in the months and years ahead. This is the core purpose of my visit," he said.
"This trip is a trade mission, yes, but I prefer to see it as a jobs mission."
His 68-strong delegation, which flew out yesterday, includes six other ministers including Foreign Secretary William Hague, Chancellor George Osborne and Business Secretary Vince Cable.
Mr Cable admitted to reporters on the trip that he was involved in a "debate" with fellow Cabinet ministers about the Government's planned immigration cap.
The Liberal Democrat said businesses from countries like India had expressed concern to him about the restrictions such a move would place on the movement of highly-skilled professionals.
He said he was committed to the coalition agreement on the imposition of a limit on non-EU nationals coming to the UK, but added: "Business is clear we want Britain to be open for business.
"We want flexibility and we want these regulations when they come in to be administered with a light touch."
Comments