At the 1996 African Championships in Athletics, aged 18, Njie won a bronze medal in the women's 800 metres (with a time of 2:10.10). She was the first Gambian runner to win a medal at the championships for an individual performance, as the country's only other medal had come in the 4 × 100 metres relay (at the 1984 event). A few weeks after her medal at the African Championships, Njie was a member of the nine-athlete Gambian delegation at the 1996 Summer Olympics in Atlanta, as the only female competitor for her country. Her only race was the 800 metres, where she failed to finish the race. She was the third-youngest runner in the event, after Ethiopia's Kutre Dulecha and Yaznee Nasheeda of the Maldives.