Acting Senior Sergeant Anthony Bond said police stopped the car at 7.30pm on Saturday and found the boy behind the wheel.
His 32-year-old father, who was intoxicated, had made him drive him to a nearby bottle store to buy more alcohol.
Investigation are ongoing.
It was also a busy weekend for police dealing with a "disappointing'' number of people who got behind the wheel after drinking, including one who was nearly three times the legal limit.
Seven people were caught over the weekend, and another case is awaiting blood test results.
Acting Snr Sgt Bond said a checkpoint in Taieri Rd between 11.10pm and 12.20am caught one person who recorded 214mcg.
The driver would be issued an infringement notice.
At 7.30pm on Saturday, a 22-year-old man was seen pulling his car into the Kensington Pub car park and stumbling out of it.
He recorded 695mcg, and was found to be a disqualified driver. He will appear in court on December 10.
Another checkpoint was held on Saturday at the north end of George St between 11.30pm and 1.30am.
Three people were processed for drink driving, recording 552mcg, 757mcg, and 807mcg, respectively.
At 1.45am on Sunday, a 28-year-old man was seen by a member of the public speeding and going through red lights.
Police found him in Highcliff Rd, and he recorded 600mcg. He will appear in court on December 17.
A 23-year-old man was seen swerving within his lane. He failed a breath test and requested a blood test.
"He was apparently the sober driver to head back with his passengers to Milton. The officers note he was clearly intoxicated.''
And at 9.45pm on Sunday, a 26-year-old woman was stopped in North Rd. She recorded 1178mcg, and will appear in court on December 18.
Acting Snr Sgt Bond said it was disappointing to see so many people still being caught drink-driving.
