The 20-year-old completed his irresistible campaign by clearly outpointing Northern Ireland teenager Joe Fitzpatrick to win gold in the lightweight division.
Flynn was followed into the ring by Prestonpans light-welterweight Josh Taylor who made it two gold medals in succession for the host nation by scoring a clear win over Junias Jonas of Namibia.
Flynn said: "As my mate Kevin from the Royal Mail would say, I'm buzzing like a jar of wasps.
"The mail man has delivered once again. They all call me a skiver at work but that's how I've got such good movement - from ducking and diving behind the bags.
"I'll be wanting my own parking space when I go back now."
Flynn rose to the occasion once again to keep the rangier Fitzpatrick at bay and seal the finest moment of his boxing career.
Flynn produced another heroic performance to match his come-from-behind victory over fancied Welshman Joe Cordina in the previous round.
Flynn, who jumped onto a corner post in celebration at the final bell, looked overwhelmed when the decision was announced.
Meanwhile Taylor could hardly hold himself together as 'Flower Of Scotland' blared out back-to-back in the cavernous 20,000-capacity arena.
It more than made up for his London 2012 heartbreak when he became the first Great Britain fighter to exit the competition.
Taylor, who had won a silver medal in Delhi four years ago, said: "I almost couldn't sing it, I couldn't hold my emotions together.
"Tears of joy, not tears of disappointment this time, thank God. I imagined it being amazing and everybody singing, but that was just surreal. It was a thousand times better.
"I could only sing it in bits because I would have broken down in tears. My body feels numb right now, I can't believe it."
England's Savannah Marshall went some way towards erasing the memory of her Olympic nightmare by winning gold in the women's middleweight competition.
The Hartlepool 23-year-old, who went into London 2012 as hot favourite but was beaten in the first round, came on strong to see off eager Canadian Ariane Fortin.
Marshall insisted there is still much more to come having only recently come back from nine months out with a shoulder injury.
Marshall said: "I think I'm far from my best and I've still got a long way to come back but I think it will just take time."
Marshall's best friend Nicola Adams added Commonwealth gold to her Olympic title with a split decision win over gutsy Michaela Walsh of Northern Ireland.
And Liverpool's Antony Fowler produced another powerful performance at middleweight to see off Indian superstar Vijender to claim gold.
Powerful England welterweight Scott Fitzgerald capped his first major international competition by blasting out another Indian, Mandeep Jangra.
The Preston man decked Jangra in the opening round and twice more in the second to secure the most emphatic of unanimous decision wins.
The 22-year-old said: "My aim was to get gold but realistically I had a lot of doubts. It's been mentally quite tough and I've just pushed through it and I got the rewards. I've got a gold medal round my neck and nothing is going to bother me now for a couple of weeks."
England's Qais Ashfaq made a good start in his bantamweight final against Northern Ireland's Michael Conlan but was outpointed by the Olympic bronze medallist.
Defiant Ashfaq said: "I know for a fact that on my day I could beat him. Next for me is the Worlds, the Europeans and then next year Olympic qualifiers.
"I'm still learning and still young - it's been an amazing experience."