The feat has been achieved in 34 years and 6 months since start of production in December 1983, the company said in a statement.
MSIL is the first car-maker in the country to cross the milestone.
"The 20 million production milestone is a testimony of trust in brand Maruti Suzuki," MSIL Managing Director & CEO Kenichi Ayukawa said.
Out of the 20 million units, 14.37 million vehicles were manufactured in Gurugram, while 5.62 million vehicles were from the Manesar facility, the company added.
The company had achieved the one million production in March 1994, nearly after a decade after start of manufacturing cars.
In April 2005, it reached the five million milestone, while the ten million mark was hit in March 2011.
"In the next seven years, the company achieved 20 million production milestone," MSIL said.
Earlier last month, the company's parent Suzuki Motor Corporation announced crossing accumulated automobile production of 20 million units in India through MSIL in which it holds 56.21 per cent stake and fully-owned arm, Suzuki Motor Gujarat (SMG) that supplies exclusively to MSIL.