The incident, which caused damage to the pitch, happened at Westfield Stadium on Saturday, November 30, during Rangers' 2-0 win in a fourth round replay.
A statement issued by the club today said: "Rangers FC has today issued an indefinite ban to a 16-year-old female who has been charged for her unacceptable behaviour at the recent Scottish Cup tie at Falkirk.
"She will be banned from attending all home and away games following the flare incident at the match. The club will continue to assist Police Scotland with their inquiries."
The 16-year-old, who has not been named, has already appeared at Falkirk Sheriff Court after being arrested.