Jackson headed home an Astrit Ajdarevic corner from a tight angle at the back post to secure the Addicks their first Sky Bet Championship win since Boxing Day.
Powell said: "This is the benchmark for what is to come over the next 17 games, I will make sure of that."
Powell was delighted at the all-round showing of his struggling side and added: "One or two things went in our favour, which is about time because we have had many, many things go against us for some while now.
"We hit the post twice in one move but they stuck at it and in the end we got our just desserts."
He reserved special praise for skipper Jackson, saying: "People look for the captain to lead the team and with John it is his goals. It was apt he scored the goal.
"Everyone really put a shift in but we are going to have to do that. We minimized their threat.
"(QPR manager) Harry (Redknapp) has an embarrassment of riches while I have just cobbled together a squad. Marcus Tudgay turned up last night and only knows my name."
Hard-working Charlton nullified the threat of their rivals from west London who have now lost three games in a row and who are slipping away from the automatic promotion places.
Redknapp's assistant manager Kevin Bond insisted QPR could not afford to worry about how their promotion rivals were doing.
Bond said: "If you start looking at the table mathematically then we don't get beat at Charlton.
"All we can do now is look at Leeds United and look to get back on track. Get back to where we were earlier in season.
"As soon as we start looking at bigger picture and promotion then we could be in trouble we need to focus on next game and getting a point."
"We shipped goals today, in a game of few chances we should have come away with at least a 0-0.
"We fell asleep and that has cost us the game."
Although QPR played the more intricate and neat football in the early stages it was Charlton who could have gone ahead after 12 minutes.
Jordan Cousins hit a cracking drive from almost 30 yards, which hit Rob Green's left upright.
Reza Ghoochannejhad snatched at the follow up, which came back off Green's left post with the keeper stranded.
Had Danny Green made a better choice the Addicks may have had another opportunity but he played a reverse pass when Cousins was far better placed.
Kevin Doyle had a shot blocked by Dorian Dervite and the ball would not fall kindly for him in another R's attack.
Nedum Onuoha went over in the box under a Michael Morrison challenge but failed to win a penalty.
Bond added: "I asked Nedum if it was a penalty and he said it was. I'm not going to be critical of the referee because they have a difficult enough job as it is, but we need those decisions to be right."