The 31-year-old Indian beat Vietnam's Le Thi Bang by a unanimous 3-0 decision to enter the final.
The five-time world champion was in fine form and her speed and guile was just too much to handle for the Vietnamese fighter.
Mary Kom peppered her opponent with multiple combination punches and didn't give her anytime to gain a foothold.
Le went for broke in the fourth and final round and managed to connect a few punches but with the Indian, having already won the previous three rounds there was very little the Vietnamese could do.
Judge A from Bulgaria ruled the bout 40-36 in favour of the Indian. Judge B of Morocco gave the same scores but Judge C of Italy awarded the fourth round 10-9 in favour of Le, however, his final scored of 39-37 went to Mary Kom.