Stephen Wilkinson had just turned 17 when the boy, Rylan, was born and was also acting as a father to his partner's two daughters from a previous relationship.
He violently shook the baby and bit his face in what was described as a "momentary loss of control" hours after returning from a night at the pub.
It was the first time Wilkinson, a gardener, and the child's mother Rebecca Costick, then 24, had been able to enjoy a night out since Rylan was born.
He later told police: "I was a good dad. I loved my son very much."
"There are few who knew this young man with his baby son who would dispute this statement," said Sally Howes QC, prosecuting.
John Coffey QC, defending, said: "It may well be that on reflection he had taken on more responsibilities than he could shoulder."
Wilkinson, now 19, of Willow Close, Beare Green, Dorking, Surrey, wept as he was jailed for four-and-a-half years, after earlier pleading guilty to manslaughter.
Rylan's mother, who was at the Old Bailey for today's hearing, also wept as details of the case were read out.
The court heard how the baby suffered bleeding and brain swelling, causing his heart and his breathing to stop.
Medical experts said his injuries were caused by "an excessive shake possibly followed by a sudden impact against a firm or hard surface".
Wilkinson initially claimed to have dropped him on his head after being woken by the baby in the night, but later said he could not remember what happened.
Both parents, and later doctors, tried to resuscitate Rylan, but he died in hospital in the early hours of October 23 2006.
He had been a "normal growing baby" who his parents planned to have, and there had been no history of abuse.
Wilkinson was said by friends and family to have been "looking forward" to his birth, and also looked after Miss Costick's two young girls with equal dedication.
"When the baby was born he was very happy and enjoyed playing an active role in the life of his son," said Miss Howes.
The teenage father would look after his son before leaving for work at 6am, and would often wash and play with him.
Wilkinson had drunk several pints of lager with his partner on the day before he killed the baby, both at lunchtime and in the evening, and Miss Costick was seen staggering out when she left the pub with him that night.
But he later claimed drink had not caused his actions when he was woken at around 4am by Rylan, who needed a feed.
Mr Coffey said: "Very often the prelude to the death of a young child at the hands of a parent will be a history of ill treatment and physical abuse. Clearly this is not such a case."
Miss Costick had told police that when Rylan was born, Wilkinson was "scared" but "didn't really change at all".
He had been "absolutely devoted" to his son, the court heard.
Mr Coffey said: "For practical purposes he was in the position of a man while he was on the very threshold of manhood himself.
"He did his best, working hard for modest financial reward but not seeking to avoid his responsibilities.
"No punishment could compare with the intensity of the punishment that he has inflicted upon himself in acting the way he did. This is something he will have to take with him every day for the rest of his life."
Judge Stephen Kramer said: "Sadly, nothing I do can turn the clock back for anybody in this family."
He accepted that Wilkinson was a "caring and devoted father".
But he added: "I am asked to regard this as a momentary loss of control and isolated incident. But you were in a position of considerable trust and what you did must have been more than momentary.
"It was a violent attack on a defenceless baby."
He said while the reasons for the attack were unclear, it appeared to have been "an angry outburst in the context of trying to console a distressed baby".
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