That huge turnout easily surpassed the previous record, set in Moscow in 2017 when 3,000 people showed up for boxing class.
Hundreds of people had gathered early for the enormous class in Zocalo plaza, which began with a tai-chi warmup, followed by a review of basic boxing movements and then practice in various combinations of blows.
Among the professional boxers who led the session were Mariana "La Barby" Juarez, a three-time World Boxing Council (WBC) champion in the flyweight, super flyweight and bantamweight categories; Ana Maria "Guerrera" Torres, a two-time WBC super flyweight champion, and David Picasso, a two-time junior champion.
"I didn't think many people would show up," 52-year-old Araceli Salazar told AFP. "I'm pleasantly surprised."
Carmen Perez, 16, an urban dance devotee, said she was thrilled to take part. "There is a very beautiful energy - very joyful, a lot of joy," she said.
The event was organized by the Mexico City government, which had recruited such prominent figures as American actor Sylvester Stallone - Rocky Balboa on the big screen -- and boxer Saul "Canelo" Alvarez to promote it.
According to mozzartsportke.com