Charlton captain Johnnie Jackson says players will reimburse fans the cost of their tickets following Tuesday's 5-0 defeat at Huddersfield.
The Addicks have gone nine Championship games without a win and are 23rd in the table, three points from safety.
Adult prices were £23 at the John Smith's Stadium, with 166 Charlton fans making the trip to Yorkshire.
"On behalf of the players, I want to apologise. It was disgraceful and you deserve better," Jackson tweeted.
The defeat at Huddersfield, which included the late dismissal of forward Reza Ghoochannejhad, followed an FA Cup third-round exit at the hands of League One Colchester on Saturday.
Supporters have held protests at The Valley in recent weeks, aimed at Belgian club owner Roland Duchatelet and chief executive Katrien Meire, voicing their concerns over the running of the club.
Interim head coach Karel Fraeye did not speak to the media after defeat on Tuesday, but goalkeeper Stephen Henderson told BBC Radio London the result left him feeling "numb".
"The lads are lower than they could ever have been in their careers," the Irishman said.
"It is a position I have not been in before. Publicly I'd like to apologise to our travelling fans for that shocking performance."
Charlton were 2-0 down at half-time and Huddersfield added three goals in the last 15 minutes to complete the rout.
"They had near 70% possession in the first half and we couldn't get near them," the 27-year-old added.
"I take responsibility for the second goal. If we go in at 1-0 we would have had a better chance in the second half.
"No disrespect to Huddersfield, but we can't be losing 5-0 to them.
"I'm not too sure what is going on."