The Pompey Problem picked up the fourth belt of his career by clinching a unanimous decision victory against Bermondsey's Chris Kongo in Gibraltar.
McKinson, 26, did enough to sway the judges in a cagey contest and take his perfect professional record to 20-0 - while inflicting a first defeat on his opponent in his 13th pro bout.
The tricky southpaw came flying out the traps, sending Kongo down in the first round and catching him by surprise.
Things settled down after the Pompey Problem's blistering beginning but he did enough to add the WBO Global belt to the WBC world youth, WBC international silver and WBO European welterweight titles that were already in his possession.
Understandably, McKinson could not contain his delight after announcing himself to the boxing world live on Sky Sports Box Office.
The Pompey Problem said: ‘I feel on top of the world.
‘Nobody gave me a chance, nobody gave me a chance except me, my team and my city.
‘My dad is a great trainer, he's finally getting the credit and I'm finally getting the credit I deserve.
‘I'm experienced, this is my seventh year as a professional, I'm finally where I want to be. We're here to stay. This is my fourth belt.
‘I told my daughter I'd bring a belt back, I'm doing it, I've done her proud.’