Lewis Bennett, 42, was sentenced at a Miami court for killing Isabella Hellmann, 41.
Bennett, of Poole, Dorset, was initially accused of her murder and intentionally sinking the ship before pleading guilty to the lesser charge of involuntary manslaughter.
The Brit must also pay about £18,000 in restitution and will spend three years on supervised release.
He apologised to his wife’s family during the hearing before US District Judge Federico Moreno rejected his defence lawyer’s request for a seven-year sentence.
The newlyweds, who recently had a baby daughter, had been sailing from Cuba to their home in Delray Beach, Florida, following a honeymoon when Bennett sent a distress signal on May 15, 2017.
Dual British-Australian citizen Bennett claimed he woke up to find his wife was missing from the 34ft vessel, Surf Into Summer.
But, he failed to report that she had vanished 45 minutes later after he fled in a liferaft.
In a strange twist, Bennett was found to have been smuggling rare coins worth nearly £30,000 which prosecutors said could have been a reason why he may have wanted his wife dead.
He had reported the gold and silver collectables from an ex-employer in St Maarten a year earlier.
Bennett had already been serving a seven-month prison term after he admitted to transporting the coins.
He was later plucked from the sea, despite an extensive search, his wife’s body was never recovered.
She was later declared dead by a judge earlier this month.
Prosecuting lawyers alleged Bennett murdered her and deliberately sank the yacht to end his “marital strife” and inherit her home and wealth, but reduced the charge to unlawful killing without malice and he later pleaded guilty.