The Pompey Problem stormed into the top five of the governing bodies standings for the first time after claiming the WBO Global belt by beating Chris Kongo live on Sky Sports Box Office last month.
McKinson, 27, with an unbeaten 20-0 record as a professional, has climbed up two positions from sixth to fourth in the updated rankings courtesy of his recent victory on the Dillian Whyte v Alexander Povetkin II undercard in Gibraltar.
The southpaw now has only American welterweight big names Vergil Ortiz jr, Shawn Porter and Mikey Garcia above him in the standings, while 37-0 man Terence Crawford holds the WBO world title.
It's yet more good news for McKinson, who yesterday signed a promotional deal with Matchhroom Boxing.
And, now standing fourth in the rankings, a potential 'Fratton Park blockbuster' mentioned by Hearn for next summer could, just maybe, be a world title fight should McKinson continue winning and rising up the WBO world rankings.