The 20-year-old has been a regular for Villa U-23 this season, bagging three goals and an assist.
A youth product of Villa, the English Forward soon got promoted to the first-team in 2017. His contract is due up next month.
Knibbs said, (h/t Birmingham Mail)
“After seven years of many ups and downs I can confirm my time at Aston Villa has come to an end.
“I’d like to thank all the coaching staff who have helped me on my journey. From joining the club as a 13-year-old I could never have imagined achieving what I have.
The English prospect hasn’t played a single game for the main team despite taking part in the training sessions of Dean Smith.
He also heaped praise on the club’s young talent and wished the Lions good luck in the Championship playoff next month.
Villa’s unwise decision
The Lions have made a huge decision in letting go of their brightest talents in the reserves.
Meanwhile, the club is on the verge of losing their prime striker Tammy Abraham, who is set to make a return to his parent club Chelsea.
Knibbs could have easily been one of the best players in the first- team had Villa opted to keep him on a permanent basis.
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The Blue and Claret army have salvaged well, with 10 straight wins after a slight dip in form earlier this year.
And it has revived the Lions’ promotion hopes as they have now secured a playoff spot.