The 34-year-old joined the Iron on Thursday morning and pens a deal until the end of the season.
Howard started his career with Arsenal and counts Cardiff City, St Mirren, Aberdeen, Blackpool (twice, and his last club before the Iron), Sheffield United and Bolton Wanderers amongst his permanent clubs.
He's also been on loan with Falkirk, Swansea City and Salford City.
In total, Howard has made 270 career appearances, and brings a wealth of experience to the squad.
He takes the Number 33 shirt and the move is subject to EFL ratification.
