Gagan Narang was born on 6 May 1983 to Bhimsen Narang and his wife Amarjit to a Punjabi family in Chennai. His father is a retired chief manager of Air India. His family comes from the Simla Gurjan Village of Haryana’s Panipat district. Due to his fathers work his family shifted to Hyderabad where he was brought up. He took to shooting when his father presented him an air pistol in 1997. He went about perfecting his shooting skills at the backyard of his home in Begumpet. According to his father, Gagan showed early sparks of his shooting ability when, at the age of two, he shot a balloon with a toy pistol.
Narang won a gold medal in the Afro Asian games, 2003 in Hyderabad on 26 October 2003 in Men's 10m air rifle competition. He won the Air Rifle Gold medal at the World Cup 2006 and followed it up with win in the event in April 2010. Gagan Narang won 4 Gold medals at 2006 Commonwealth Games.
Narang qualified for the 2008 ISSF World Cup Final after he won a gold in the World Cup in China earlier in 2008. On 4 November 2008, he broke Austria's Thomas Farnik's record, set in the 2006 World Cup final in Granada, Spain.
Narang won 4 Gold medals at the 2010 Commonwealth Games in New Delhi. Gagan also clinched a silver medal in the Asian Games 2010. He also combined with Abhinav Bindra and Sanjeev Rajput to win the country another silver.
Narang won the bronze medal in the 10m air rifle event at the 2012 London Olympics becoming India's first medal winner at the 2012 games. This win made his only the 3rd shooter from India to medal at the Olympics. Gagan was just behind the silver medallist Niccolo Campriani of Italy, while the gold medallist Alin George Moldoveanu of Romania. However he failed to qualify for the finals of the men's 50-metre rifle three positions at the Royal Artillery Barracks.
Narang won 1 silver medal and 1 bronze medal in 50-metre rifle prone and 50-metre rifle 3 position respectively at the 2014 Commonwealth Games in Glasgow.