Oliver Wareham, 29, of Rownhams Road, Southampton, pleaded guilty to causing the death of William Gaskin by driving without due care and attention while over the prescribed limit.
Winchester Crown Court heard how Wareham’s Volkswagen Bora was in collision with a pony and trap on Portsmouth Road, on 26 March.
Mr Gaskin, 33, from Guildford, was travelling in the trap and suffered life-threatening injuries.
He was taken to Southampton General Hospital where he died a short time later.
The prosecution told the court how Wareham initially stopped at the scene but had left before police had arrived, leaving the car there.
However, he called police the next day admitting that he was the driver.
The hearing heard how investigations by the Serious Collision Investigation Unit revealed that the car had been travelling at a minimum of 57mph prior to the collision, on a road with a 40mph limit.
The prosecution also explained that while Wareham did flee the scene and did not contact police until the next day, further investigations by officers proved that he had been drinking.
Using CCTV from the pub where he had been drinking and evidence from the till receipt system, officers were able to identify what he had been drinking that evening, putting him over the drink-drive limit.
Today Wareham was sentenced to four years and four months and disqualified from driving for five years, with an extended retest.
Sergeant Rik Grant, from the Serious Collision Investigation Unit, said: “Sadly this was a totally avoidable death.
“Had it not been for the reckless decisions of Wareham, who not only got behind the wheel that night after drinking alcohol all evening, but also ignored the speed limit, Mr Gaskin would be alive today.
“Our investigations found that had he been driving at 40mph, at the point he started braking he would have stopped without hitting the pony and trap.
“Not only did his actions that night cause this fatal collision, he then left the scene in an attempt to cover up the fact that he was drink-driving.
“But despite his attempts, our thorough investigations have ensured that a dangerous driver has been taken off our roads.
“It is never worth the risk to drink-drive or speed and sadly as this case has proved, the consequences can be fatal.”