Scott Allen Orrock, 47, was accused of setting a police van on fire outside his Newtown tattoo parlour in the early hours of April 20 last year.
He pleaded not guilty on the grounds that he set the paddy wagon on fire in order to protect himself and his family from bikies.
Orrock is said to be a former boss of the Nomads bikie gang, and is currently an associate of the Hells Angels.
His trial, which started in the District Court in Sydney two weeks ago, was aborted last week for legal reasons.
On the first day of a second trial on Tuesday, Orrock pleaded guilty to intentionally damaging police property by fire.
Last week, he was acquitted of four counts of intimidating police after the judge ruled there was not enough evidence.
Orrock's case provoked the ire of NSW Premier Barry O'Farrell last year after he was initially granted bail in the Local Court.
The Director of Public Prosecutions (DPP) lodged a bail review the very next day and Orrock's bail was revoked by a Supreme Court judge.
Orrock attempted twice more to get bail in both the Local and District Courts, but both applications were denied.
He will face a sentence hearing at a later date.