He remains on bail and is expected to receive his sentence in around three weeks' time.
Hillgrove, who has handled PR for BBC show Dragons' Den businessmen James Caan and Duncan Bannatyne, was found guilty on both charges of tax fraud by a unanimous verdict.
He was accused of failing to pay £93,000 in VAT and PAYE.
Hillgrove, who represented himself and pleaded not guilty, is planning to appeal against the verdict.
