The Hollywood star was met by a media scrum when he arrived at Mullumbimby Local Court on Wednesday wearing a sage green suit.
The 55-year-old was seen driving erratically on Booyong Road in the state's northeast by police for around 8km about 2.11am on July 20, the court was told.
Magistrate Kathy Crittenden said there were "unusual" circumstances, with a worldwide Microsoft outage ensuring police systems were offline and a breath test could not be completed.
"Ordinarily police would've proceeded with a breath analysis but they had to use the old- fashioned sobriety test," Ms Crittenden said.
Baker was observed to be unsteady on his feet and smelt of alcohol, telling officers he had consumed four glasses of wine at a dinner from 6pm.
"(Baker) was very polite and co-operative ... extremely remorseful for his actions," Ms Crittenden said of Baker, who was the vehicle's sole occupant.
Baker has since completed a certificate in a traffic offenders rehabilitation program, the court was told.
Simon Baker was "very polite and co-operative ... extremely remorseful," a magistrate said. (Darren England/AAP PHOTOS)
Ms Crittenden said four character references had been tendered to the court about Baker's community contributions, significant remorse and his conduct being out of character.
"The court has little difficulty in finding that Mr Baker is remorseful for his offending and it is unlikely he will offend again," she said.
Baker, who previously pleaded guilty to driving under the influence of alcohol, received a nine-month good behaviour bond and no conviction was recorded.
The actor is back in Australia after a stellar TV and movie career overseas.
His most prominent role was on the hit TV show The Mentalist, enjoying a seven-season run playing a California Bureau of Investigation consultant.
It earned him a number of award nominations, including a Primetime Emmy nod for outstanding lead actor in a drama series.
Simon Baker is back in Australia after a stellar TV and movie career overseas. (Darren England/AAP PHOTOS)
Baker featured in some classic Australian TV programs including Home and Away and Heartbreak High, earning him Best New Talent at the 1993 Logies.
He made the move to the United States, landing roles in films such as L.A. Confidential and The Devil Wears Prada.
Baker was given a star on the Hollywood Walk of Fame in 2013.
He returned to Australia, recently starring in the Netflix series Boy Swallows Universe which won several Logies.
6°C