The 29-year-old Asian Games gold medallist was handed the suspension by National Anti Doping Agency's (NADA) disciplinary panel.
The verdict of the NADA panel is based on the result of a test conducted on the athlete last year.
"She has been suspended for eight years with effect from July 2016," NADA chief Navin Agarwal told PTI.
Priyanka's samples had tested positive for mephentermine (a stimulant).
As per the NADA code, athletes caught for a second anti- doping rule violation get a sanction ranging from eight-year to a maximum life-time ban.
A gold medallist in 4x400m women's relay at the 2014 Incheon Asian Games, Panwar had tested positive for a banned stimulant during a national inter-state athletics competition last year.
She had then decided to face the disciplinary panel.