The Indian boxer, who is a five-time world champion, took bronze at the London Olympics 2012 here on Wednesday after bowing out in semi-finals.
At the ExCeL South Arena here, "Magnificent" Mary went down to Great Britain's Nicola Adams (second seed) in the women's 51kg semi-finals and will receive a bronze medal.
Nicola started off well by taking the first round 3-1 with a couple of strong punches. After the second round, Nicola enjoyed a 5-2 advantage. Nicola extended that to 8-4. The final verdict was 11-6 in favour of the home boxer.
She might have lost but the entire country was behind her in this fight. She gave her best and ended second best. But she can hold her head high after having come to this stage despite lot of hardships.
The 29-year-old Mary had lost to Nicola in May at the World Championships. It is second successive setback in four months.
Mary is the third Indian woman to secure an Olympic medal after Karnam Malleswari (2000 Sydney, bronze) and Saina Nehwal (bronze, London Olympics 2012).
The losers of both semi-finals will be awarded bronze medals.
This is the first time, Women's boxing has been included as a medal sport in Olympics.
Earlier in the day, Mary had tweeted (@MaryKomIndia): "Ready for my match. Thanks all for your wishes. Hope to make my country proud. Jai Hind!"
India cricketer Zaheer Khan tweeted (@ImZaheer): "Very excited to watch @MaryKomIndia in action this evening. Truly proud of her - a true role model for India and its women."
On being at the London 2012 Olympic Games, she said, "The Olympics are very special. Every athlete works to play at the Olympic Games. This is my 12th year of fighting and I came back out of retirement and changed my weight because I had to take part in the Olympic Games."
Mary had outclassed Tunisian opponent Maroua Rahali 15-6 in the quarter-finals on Monday. She had 2, 3, 6 and 4 points, respectively, in the four rounds. Rahale had 1, 2, 1 and 2 points. Mary dominated all the way.
Earlier, Mary had won her Round of 16 bout against Poland's Karolina Michalczuk 19-14 on Sunday.