The 21-year-old lit up St Andrew's with a stunning run and finish to put the seal on victory after Grant Hall's opener.
Warburton was thrilled with the quality of the strike and feels it is reward for Osayi-Samuel's patience.
"I think that goal warmed the whole stadium," said Warburton.
"Anyone who loves football would have enjoyed that goal. Osayi-Samuel showed his power, his desire and to finish that type of run with that level of quality was first class.
"He is a young player that's learning. He's had to be patient to earn his chance and I'm very pleased for him."
Rangers captain Hall started it all late in the first half with his third goal of the season.
He had seven games on loan with Blues from parent club Tottenham five years ago, prior to a permanent move to QPR.
Birmingham were picked off again in the 67th minute when Osayi-Samuel started from inside his own half and surged past everyone, holding off Blues defender Maxime Colin, before firing home.
"I think if Colin had not been booked earlier he would have fouled Osayi-Samuel and stopped him," admitted Birmingham manager Pep Clotet.
"But we had no cover for Colin either and Osayi-Samuel was able to get deep into our defence.
"However, I have to say it was a good goal, even if from my point of view we could have defended it better."
There was a minute's applause before kick-off for Jim Smith and Ron Saunders, former Birmingham managers who both died this week.
Present boss Clotet is trying to fashion a team that is both easy on the eye and successful but on this evidence he's got a long way to go.
Rangers had just ended a damaging run of seven games without a win by beating Preston on Saturday and were desperate to build on that.
QPR hadn't kept a clean sheet all season until Preston failed to score against them and Birmingham found it surprisingly difficult too, despite dominating most of the first half.
In a minute of added time Eberechi Eze lifted a free kick into a bunch of players and Birmingham failed to deal with it.
The ball skimmed off Kristian Pedersen's head and out of the scramble, Hall got the ball over the line from close range.
Referee Darren Bond missed an offside that would have ruled out the goal, but honest Clotet said: "It might have been offside but was very hard for the referee or the linesman to see it.
"We won't use that but look at how we could have defended it better."