Charlton will travel to Swansea City U21 in the next round of the Checkatrade Trophy.
The Addicks were guaranteed an away tie after finishing as runners-up in Southern Group A.
Charlton won two of their three group matches to reach the last-32 stage of the competition.
A 2-0 away win at Crawley Town in August was followed up by a dramatic 3-2 home victory against Fulham U21 a fortnight ago, which sealed progression into the next round.
The ties are due to be played in the first week of December.
Read Time: 1 mins