Located in Noida, India, on the outskirts of New Delhi, the factory will almost double Samsung's Noida unit capacity from around 68 million units a year to 120 million annually according to a report from Bloomberg.
In his address at the Samsung event, Modi said that development would lend pace to the Make in India programme.
The Samsung unit was set up in Noida back in 1995 and it was used to initially produce television sets.More news: India's Supreme Court upholds death sentence in Delhi rape case
"India is now second in terms of phone manufacturing".
The facility was jointly inaugurated by Modi and Moon Jae-in, President of the Republic of Korea.
Speaking on the occasion, the Prime Minister described the occasion as a special one, in the journey to make India a global manufacturing hub. "Altogether, over 400,000 people are working in those units and Samsung is spearheading this with a workforce of 70,000 people", Modi said.
Last year, Samsung announced budget of Rs 4915 crore to expand the phone manufacturing factory, and now, the plant is ready to manufacture nearly every model of Samsung.More news: Thai cave rescuers free three more boys
He said the plant and what it represents for the two countries will go down in the history of bilateral relations of India and Korea.
India is a country with a population of 1.3 billion people, and yet there are only 425 million smartphone users.
Samsung, which has been assembling phones in India since 2007, also plans to export India-made handsets.
Samsung is expected to create 15,000 jobs through the new manufacturing unit.
70,000 employees are now working for Samsung, and they are looking forward to expand their offline presence to 1.5 lakh retail outlets.More news: 3rd T20I ENG vs IND Live Streaming
The more than 500 Korean companies operating in India were mostly concentrating in the automobiles, electronics and textiles "but going forward, we will expand cooperation to various areas, including shipbuilding, medical devices and food processing", Moon said. "India is going through digital transformation and I encourage more companies from South Korea to come and invest here", Modi noted. "India has become number 2 in mobile phone manufacturing".