Caleb Rogers is one of two people facing legal action from gaming studio Epic Games for using cheat software to play the free game Fortnite.
The studio says it has taken the step because the boy declined to remove a YouTube video he published which promoted how to use the software.
His mother says he is a scapegoat.
"This company is in the process of attempting to sue a 14-year-old child," she wrote in the letter which has been shared online.
Ms Rogers added that she had not given her son parental consent to play the game as stated in its terms and conditions, and that as the game was free to play the studio could not claim loss of profit as a result of the cheats.
"It is my belief that due to their lack of ability to curve cheat codes and others from modifying their game, they are using a 14-year-old child as a scapegoat to make an example of him," she said.
In a statement given to the website Kotaku, Epic Games said the lawsuit was a result of Mr Rogers "filing a DMCA counterclaim to a takedown notice on a YouTube video that exposed and promoted Fortnite Battle Royale cheats and exploits."
"Epic is not OK with ongoing cheating or copyright infringement from anyone at any age," it said.
Cheating for fun
In a YouTube video made by the boy himself discussing the legal action, he said he cheated "for fun" and that the cheat he used was freely available online. He denied making it or selling it himself.
He admitted that he had been banned from the game several times previously.
The video received a mixed reaction, with some comments supporting him but many saying he was in the wrong.
Epic Games has been contacted by the BBC for comment
Photo copyright: EPIC GAMES