The youngster, still just 19, capped his loan spell at Rangers with the biggest game of his short career - the Second Division Play-Off Final against Cardiff City.
The Millennium Stadium was packed with 66,000 fans but Stephen did not appear overawed by the occasion and put in another fine display at right-back.
However, having finished goalless at full time, Cardiff substitute Andy Campbell lobbed ex-Spur Chris Day in the QPR goal just six minutes from the end of extra time to take Lennie Lawrence's men into Division One.
Kelly played nine games in his loan spell at Loftus Road - Sunday was his first defeat.
Spurs loanee Stephen Kelly played the full 120 minutes as QPR's promotion dream was shattered at the Millennium Stadium on Sunday.