The 42-year-old pleaded guilty to drink-driving after his black Mini collided with two other cars in Richmond, west London on March 18.
He has also been banned from driving for 20 months.
District Judge Barbara Barnes told McPartlin, "At the time when it happened you were struggling with various personal problems and also alcohol issues for some months.
"This incident happened, sadly, when it seems you suffered a brief relapse... I think it will have quite an impact on you to know you're no longer a man of good character."
The court heard that in a statement to police McPartlin said: "I am very sorry I did this. I am ashamed and mortified that this happened... I accept full culpability for this and wish to apologise to all those concerned."
The charge stated he had 75 microgrammes of alcohol in 100 millilitres of breath. The legal limit is 35 microgrammes per 100 millilitres of breath.
McPartlin, who lives in Chiswick, west London, was arrested at around 4pm on March 18 after a failing a roadside breathalyser test following a collision between the Mini he was driving and two other cars.
The Metropolitan Police previously confirmed that a number of individuals were treated at the scene for minor injuries, and a child passenger from one of the cars was taken to hospital to be checked as a precaution.
But ITV confirmed Donnelly will be hosting the live shows without his TV partner of almost 30 years.