In 2019, it was revealed that Niyonsaba was born with the 46,XY karyotype and an intersex condition after her qualification for IAAF women’s competition was affected by the association’s new regulations for athletes with XY disorders of sex development, testosterone levels above 5 nmol/L, and androgen sensitivity.

In 2017, Niyonsaba earned a new personal best and national record at the Monaco Diamond League after winning the 800m there in a time of 1:55.47, on July 21. With this time she was the World No. 1. heading into the 2017 World Championships in London.

In 2016 Niyonsaba won the 800 meters at the 2016 IAAF World Indoor Championships in 2:00.01. Later that year Niyonsaba carried the flag for Burundi at the 2016 Olympic Games in Rio. She concluded her competition with her first Olympic medal, a silver in the women’s 800m in a time of 1:56.49, behind Caster Semenya of South Africa.

She is the National record holder in the event, improving her own record to 1:58.67 on August 9, 2012 in the semi-final round of the Women’s 800m event at the 2012 Summer Olympics. It was a 0.01 seconds improvement on her previous record. Two days later she finished seventh (subsequently upgraded to fifth as a result of the doping disqualifications of Russian athletes Elena Arzhakova and Mariya Savinova) in the 2012 Olympic final. Less than a month later she took the record down yet again to 1:56.59.

She had a quick rise to prominence in 2012 while still a teenager. The first time she set the record was in late June 2012 while narrowly winning the 2012 African Championships in Athletics in 1:59.11 in what was only her third competitive race. At that, she improved upon her own previous national record of 2:02.13, set in the qualifying round. In the opening round race, the inexperienced runner had opened up a 30 meters lead the pack.

Three weeks later on July 20, 2012, she improved the record again to 1:58.68 while finishing second at the 2012 Diamond League meeting at Herculis.

Francine Niyonsaba (born May 5, 1993) is a Burundian runner who specializes in the 800 metres. She is a 2016 Olympic silver medalist in the 800 metres. Her silver medal was the first Olympic medal for Burundi since 1996. Niyonsaba finished second in 800 meters 7 race series of 2016 Diamond League. She improved her personal best to 1:56.24 at 2016 Herculis meet.