State media said Gu was charged in Anhui province along with a second person named Zhang Xiaojun, leading to speculation the charges involve the November 2011 poisoning death of British businessman Neil Heywood.
The Wall Street Journal said Gu may have believed Heywood threatened the safety of her son amid reports of wide-ranging corruption and conflicting economic interests involving family members of the former Communist party chief of the city of Chongqing. She was charged with intentional homicide.
Her husband was ousted as party boss of Chongqing in March. Bo Xilai had once been considered a likely candidate for a future top leadership of China.
Chinese police began re-investigating the Heywood case in April.