Jonny signed for Boro in July 2017, arriving from Norwich City.
A product of the Leeds United Academy, Jonny made his professional debut as a 16-year-old and went on to make over 200 appearances for his hometown club before being sold to the then-Premier League Canaries.
Howson was a striker as a schoolboy and has scored over 50 career goals. A former team-mate of both Adam Clayton and Patrick Bamford, he had captained both Leeds and Norwich and brought a wealth of experience.
He made 48 appearances in the 2017/18 season, scoring three goals. It was a season that saw him break through the 400 career starts mark.
The 2018/19 campaign added another 47 games to his collection. It was a season that saw the occasional appearance as captain, a new position of right-back for a few games and reach the milestone of 400 league starts in the final game of the campaign at Rotherham.