The African country now has 11 medals, including five gold, at London 2012 and all have come in the same sport at ExCeL.
Obiji lifted 145kg with her opening attempt and that was enough to see Randa Mahmoud of Egypt into silver, although the 21-year-old had to nervously watch on as the Egyptian tried and failed to lift 145kg with her final attempt.
Obiji said: ‘I feel like I could shout, I'm so happy. It's my birthday next Tuesday so it's now a double celebration - I'm going to be celebrating all month.
‘This is my first outing at the Paralympic Games. I started training in 2006, I love powerlifting, I love my game and I love sport.’
China’s Xu Yanmei was in third for most of the competition, before Mexico’s Catalina Diaz Vilchis achieved 128kg with her last lift. But the Chinese athlete responded to lift just 1kg more to claim bronze.
In the men’s -82.50kg event, Majid Farzin took gold for Iran with a best lift of 237kg, although he also had an anxious wait to see if victory was his.
China’s Gu Xiao Fei attempted a lift of 238kg in the last round after Farzin had completed his three attempts, but the 23-year-old was unsuccessful and had to be content with silver with a best of 228kg.
Bronze went to world champion Metwaly Mathana of Egypt with a best of 227kg.
Farzin said: ‘I was worried about waiting for the result. If Gu had made his lift, he would have won so I was worried.’
The Egyptians were celebrating their third Powerlifting gold medal of the Games in the final event of the day as Hany Abdelhady won the men’s -90kg title.