The 26-year-old was charged in November with misconduct, breaching the rules 232 times between 2017 and 2021.
"In addition to the previous charge, it is alleged that the Brentford FC forward breached FA Rule E8 a further 30 times between March 14, 2017 and Feb. 18, 2019," the FA said in a statement.
A report in the Daily Mail newspaper in November said Toney had been under investigation for around seven months in relation to the alleged betting activity before he played for Brentford.
It added there were no suggestions that he had bet on his own team to lose matches.
After the newspaper report, Toney said he was assisting the FA with its enquiries.
Brentford said in a statement that private discussions with Toney and his legal representatives would continue but made no further comment.
Toney, who has scored 10 goals in 14 Premier League games this season, was not called up by England for the World Cup. The FA said Toney has until Jan. 4 to respond.