The driver of a black BMW which was hit by Ant's vehicle described it as going round the corner "like a rocket".
The charge states he had 75 microgrammes of alcohol in 100 millilitres of breath, the legal limit is 35 microgrammes per 100 millilitres of breath.
Meanwhile a witness statement from a driver of one of the two cars involved in the collision with McPartlin said that he and his wife "could have died as a result of Mr McPartlin's reckless driving".
The driver of the other Mini auto also told the court they thought they could have died in the incident.
The 42 year old pleaded guilty to drink-driving after his black Mini collided with two other cars in Richmond, west London.
Ant was also banned from driving for 20 months, however, his legal representatives requested Ant complete a drink-driving course in order to reduce that ban to 15 months.
District Judge Barbara Barnes told Ant: "You are a well-known and successful entertainer", whose weekly income is estimated to be around £130,000 a week.
The judge said: "You were a man of good character. you have lost that good character".
In a statement read out in court, McPartlin said he "accepts full responsibility" for the incident. He said that he would be getting specialist help to "ensure that nothing of this nature happens again".
In a statement to police, Ant apologised for his actions, which he said have left him "ashamed and mortified".
His defence barrister, Liam Walker, told the court: "Anthony McPartlin is sorry".
And the star will also be absent from the Britain's Got Talent live semi-finals next month, leaving Dec to present alone.