The app is called BHIM (Bharat Interface for Money) -- a re-branded version of UPI (Unified Payment Interface) and USSD (Unstructured Supplementary Service Data).
Speaking on the occasion, Modi said BHIM app was very simple to use and a thumb impression was enough to operate it.
Modi said the government was working to launch a new security feature, by using which transactions could be carried out without a phone and Internet etc.
"Be it a smartphone or feature phone of Rs 1,000-1,200, BHIM app can be used. There is no need to have Internet connectivity. One only needs a thumb. There was a time when an illiterate was called 'angutha chchap'. Now, time has changed. Your thumb is your bank now. It has become your identity now."
He dedicated the new app to Dr B.R. Ambedkar and said: "The mantra of Dr Ambedkar was to work for the uplift of the poor. And the biggest power of technology is that it can empower the poor."
Taking a dig at the Congress, Modi said during the earlier United Progressive Alliance rule at the Centre, money lost in the scams made news but now the nation is talking about money coming back into the system.
"Look at the newspapers or video clips from three years ago -- the news was all about what we lost in scams. However, today, it is about what has come back or what is the gain," Modi said.
The Prime Minister recalled the days when India was called 'sone ki chidiya' (bird of gold) and said the nation still had the potential to become the same again.
He said boosting digital connectivity will "do wonders for our nation", adding that the day was not far off when the cash-based transaction will turn completely digital.
Making a pitch for digital transactions, Modi said 'Lucky Grahak Yojana' and 'DigiDhan Vyapar Yojana' were a Christmas gift to the nation.
Over 100 days, several prizes of Rs 1,000 will be given to people through lucky draws. The mega draw will be held on April 14, the birth anniversary of Dr Ambedkar, he added.