Hubbard, 54, faces up to five years in state prison when he returns to court for sentencing Feb. 23.
Hubbard was convicted of ordering two unauthorized payments to former BHUSD facilities director Karen Christiansen totaling $20,000. The school board never authorized the payments.
Hubbard was also convicted of increasing Christiansen's monthly car allowance from $150 per month to $500 per month.
The district attorney's office argued Hubbard and Christiansen had a "special relationship."
Christiansen, 53, was sentenced to five years in state prison for conflicts of interest in contract negotiations between the BHUSD and company she consulted for.