Afterwards Pearson was left kicking himself as the Foxes failed to take a number of their chances.
"We created chances throughout but couldn't take them," admitted Pearson.
"It was a bit of a reality check at half-time and I was happy with response in the second half. Even though we conceded two we had enough opportunities to get something out of it, so we have missed a trick.
"There will be days when we create less chances and win. But you have to give Charlton credit. Chris [Powell] will be happy with a hard-fought victory - but I expect to get something out of a game like that."
Next up for Leicester is a trip to Ewood Park to face Blackburn Rovers on Saturday.