The ban was announced late on Thursday three days after a stray string - covered with a glass powder paste - slit the throat of a four-year-old boy as he passed through an upscale neighbourhood on his father's motorcycle.
Some kite fliers reinforce their strings with wire or ground glass so that they can duel against other kites. When strings cross in the congested sky, the winner cuts loose the opponent's kite.
The bleeding boy, Shayan Ahmad, collapsed and died in the lap of his father before he could be taken to hospital.
The tragedy brought the death toll from such incidents to seven in the past two weeks. Politicians and human rights activists had been calling for a ban on a kite-flying festival planned for Sunday.
The provincial government in Lahore announced on Thursday night that the ban on kite-flying was immediate and that violators would be arrested.
Ahmad's father Mohammed Rizwan welcomed the ban.
"I saw my son dying helplessly," Rizwan said. "My son's death has ruined my life."
The festival, Basant, marks the arrival of spring, and during the two days of festivities the sky is covered with thousands of kites.
However, the use of dangerous strings has turned the centuries-old pastime into a deadly sport.
All seven people killed recently were riding on motorcycles, says the Lahore police chief, Khwaja Khalid Farooq.
"We are doing our best to control the sale and manufacturing of glass and chemical coated strings. We have arrested 1100 people since 5 March for selling or using prohibited material in the kite flying," he added.