The 41-year-old had 58 microgrammes of alcohol in his breath on the day of the accident in Edinburgh where he was performing in the Queen-themed We Will Rock You stage show at the city's Playhouse Theatre. The legal limit is 35g.
But his pleas of not guilty to three other charges, including an allegation that he drove without due care and attention on 18 December last year, were accepted by the Crown.
Sentence was deferred until next month at Edinburgh Sheriff Court when he faces trial on one charge of possessing an offensive weapon called a kubotan, a small martial arts stick which often doubles as a key fob.
A motion for his vehicle to be forfeited will also be considered by the court next month. Sheriff James Scott also disqualified the actor from holding or obtaining a driving licence in the meantime.
Day was arrested in the early hours of 18 December after an accident which damaged a lamppost in the city's Manor Place in the West End.
The entertainer, of Clacton-on-Sea, Essex, had denied all the charges against him during two previous hearings at Edinburgh Sheriff Court and he was due to go on trial today.
But during a procedural hearing yesterday, solicitor Robert Frazer told the court his client would plead guilty to two of the charges he faced.
Sporting a grey goatee beard and wearing a grey suit, Day dodged questions as he entered Edinburgh Sheriff Court. Hanging his head in the dock, Day simply said "Yes I am" when asked by Sheriff Scott whether he was pleading guilty to two of six charges.
He admitted one charge of failing to stop at the scene of the accident. He further pleaded guilty to driving in Manor Place, Balfour Street and other roads in Edinburgh while over the drink-drive limit.
His pleas of not guilty to allegations he drove without due care and attention, failed to report the accident to police and failed to co-operate with a preliminary breath test were accepted by prosecutors.
Day also denied possessing an offensive weapon, namely the kubotan, but the plea was not accepted by prosecutors.
Trial on that charge was fixed for 18 February, with a procedural hearing set for 10 February.
Sentencing on the two charges he admitted was formally deferred to the next hearing. The court will also decide at a later date whether his car should be taken away permanently.
Day spoke briefly to reporters as he left court but said he could not comment on the case at this stage. He said: "The show went great. I love Edinburgh."