Goals from Dennis Rommedahl, Chris Perry and Darren Bent helped Charlton maintain their perfect start to the Premiership season at Middlesbrough.
Rommedahl struck on 38 minutes, sending a fine first-time effort past Mark Schwarzer to give the Addicks the lead.
Perry's side-footed finish from Danny Murphy's free-kick nine minutes before the end put Charlton in control.
Bent ran clear and slotted home in injury-time to seal a deserved victory against a lacklustre Boro side.
Yakubu headed over early on from Stewart Downing's incisive cross but that was about as close as the home side came to scoring.
Downing also shot over after some good work from Michael Reiziger but Charlton always looked threatening on the break.
Rommedahl in particular was causing problems and produced several marauding runs which just lacked a final ball.
But the Dane put Charlton ahead when he latched on to Danny Murphy's through-ball and rifled a left-foot shot past Schwarzer and into the corner of the net.
Boro could have been level inside two minutes after Franck Queudrue's shot sparked a goalmouth scramble, but Charlton eventually cleared.
James Morrison forced a full-length save from Stephan Andersen as Boro finished the first half strongly.
Middlesbrough gave Emanuel Pogatetz a debut in the second half, the £1.8m signing replacing Franck Queudrue at left-back.
The Austrian international was only given clearance to play this week following the reduction of a ban imposed by the Russian Football Association.
Boro were still struggling to impose themselves on Charlton, however, and were thankful for some wasteful crossing when the visitors were well-placed.
Mark Viduka saw a shot saved by Andersen but, at the other end, Bent sent a strike just wide.
The home fans became increasingly edgy as the clock ticked away but, apart from a Massimo Maccarone shot which gave Andersen some trouble, they had precious little to cheer.
And it was little surprise when Perry doubled the Addicks' lead with a shade under 10 minutes remaining, side-footing neatly home from Murphy's low free-kick on the right.
Boro tried pushing forward for a consolation, but were caught on the break in time added on, when Bent ran clear before finishing with aplomb.
Middlesbrough boss Steve McClaren:
"I'm shocked, angry and disappointed. I can offer no excuses for that display. It was unacceptable.
"It was very poor, not the Middlesbrough we have come to know. It was possibly the worst performance I have seen since I came here.
"The fans pay their money and the players let them down. We have to make sure we give them more in the future."
Charlton boss Alan Curbishley:
"That was a great performance. There is a long way to go but this was a big game for us today.
"We can go into the two-week break happy and I hope the international players come back OK, then the away game at Birmingham is just as tough.
"We thoroughly deserved this. People will say we scored in the last minute but we deserved to score three."
Middlesbrough: Schwarzer, Reiziger, Ehiogu, Southgate, Queudrue (Pogatetz 45), Morrison (Mendieta 45), Parlour, Boateng, Downing, Viduka, Yakubu, Mendieta (Maccarone 58).
Subs Not Used: Doriva, Jones.
Booked: Southgate, Reiziger.
Charlton: Andersen, Young, Perry, Hreidarsson, Powell, Rommedahl, Murphy, Kishishev, Smertin (Hughes 83), Thomas (Bartlett 78), Bent.
Subs Not Used: Spector, Fortune, Myhre.
Goals: Rommedahl 38, Perry 81, Bent 90.
Att: 26,206 Ref: M Dean (Wirral).