The US singer - real name Peter Gene Hernandez - was found by police officers with 2.6 grams of a "white powdery substance" which tested positive to the illegal drug at the Hard Rock Hotel And Casino in Las Vegas.
Although he was booked on a felony charge of possession, however, no formal charges have yet been brought against the 'Just The Way You Are' singer as the case is being reviewed, according to the Clark County District Attorney's Office.
According to a copy of the arrest report, a bathroom attendant told a member of the security team there was a man he believed was taking drugs in the toilet, and that he was "taking a really long time".
When he eventually left the cubicle, the singer was asked to hand the security guard whatever narcotics he had on him.
The report states: "This is when Hernandez, with his left hand, pulled out a white powder substance, which was consistent with cocaine, from his left-front jeans pocket."
He then reportedly said, "Can I speak to you honestly, sir?" before admitting he "did a foolish thing and has never used drugs before".
Bruno was arrested after tests proved the substance was cocaine and he was taken to the Clark County Detention Center where he was booked for the possession of a controlled substance.
Bruno - who is best known for co-writing and appearing on the songs 'Billionaire' with Travie McCoy and 'Nothin' On You' with B.o.B - had performed at the hotel earlier in the night.
He was released from police custody at around 7.45am Sunday morning and is due to return to court on November 18 for his arraignment.