The club have also slashed 20% off all adult season-ticket prices and will cut the size of their playing squad next season in order to subsidise the reduction.
Mr Ennis told the club's official website: "In these tough times it's fantastic to see Barnsley Football Club put its fans before finance and cut the price of season tickets at Oakwell yet again.
"The decision to extend the offer of free tickets to all youngsters under 12 can only help bring more families to Oakwell.
"It's fantastic to see the club do this again. I would urge every Barnsley fan to get behind the club and the team and help forge a bright future together by booking their family's seats at Oakwell for next season."