They now need just three more points but could become champions on Monday if Burnley lose at home to Wigan.
David Nugent's goal in the 67th minute settled a hard-fought match and was the striker's 21st of the season and his 19th in the Championship.
Pearson said: "We deserved to win the game and we created more opportunities.
"We are in a good position and I thought this was a very interesting and tactical game between two good sides. But I have not changed my philosophy. We have three games left and we want to win them all.
"I think QPR have a lot of quality players and today showed their depth of quality.
"It was always going to be a tough game for us to win and both games against QPR have been decided by one goal and fittingly each time it was a quality goal.
"So I am really pleased we have won the game and shown the discipline we have had all season.
"The players showed a lot of focus and a real understanding of playing different systems. We have shown an adaptability that, moving forward is going to be important for us.
"We won't be able to dominate the Premier League like we have the Championship but we want to be competitive next season."
Nugent's goal was set-up by an excellent pass from Danny Drinkwater and the striker finished it off with a low angled shot across Robert Green into the corner of the net.
QPR had their chances, the majority of them falling to Modibo Maiga, but he was off target with his shooting and also twice denied by excellent saves from Kasper Schmeichel.
To add to QPR's problems, they had Benoit Assou-Ekotto sent off in the 78th minute for a foul on Andy King that earned him a second yellow card after being booked in the first half for a tackle on Riyad Mahrez.
QPR manager Harry Redknapp is also looking for one more win to ensure his side's place in the play-offs although the former Tottenham boss believes they might have enough points already.
He said: "We still need another result. We are still one result away from doing it - although you never know do you?
"We might not have to win another game. We might have enough points already, but we don't want to leave that to chance. So we are looking for another win.
"I thought we played well today and were unfortunate to lose.
"Leicester have done fantastic and have had a great season. They are a good side but I thought we were every bit as good as them today.
"We had some good opportunities but that's the story of our season - we have not taken the opportunities when they have arrived.
"You have got to stick one away. That's the difference really. They got the one chance with Nugent and he scored while we got in three or four times and couldn't score."