The 21-year-old Ghanaian netted a sensational curler at the Valley last month to secure his side a memorable 1-0 victory.
He followed that goal up with another effort in the 2-0 English Championship win over Birmingham and provided the assist for Ricardo Pereira's equaliser in the 2-2 draw with Oxford United last time out.
Issahaku said on Ghanasoccernet: "I'm really pleased and very proud to have won Goal of the Month. That goal was special, especially after missing so much football last season.
"It wasn't just down to me, though; the whole team played well that day. Charlton are a good side, but we fought hard and got the three points.
"Scoring that winner was a reward for all the effort. I always try to give everything, so it means a lot when I manage to score and help the team.
"Thanks to my teammates, the staff, all the fans - their belief drives me on. Let’s keep going and hopefully there are lots more moments like this ahead."
Tottenham Hotspur gave Roberto De Zerbi plenty to smile about as they cruised past Charlton Athletic 5-1 in the Carabao Cup, with new signing Savio marking his debut with a goal.
Kenya international midfielder Timothy Ouma has joined English Championship side Charlton Athletic on loan from Slavia Prague.
New Manchester City signing Jeremy Monga claims it was a "no brainer" decision to join the club over Premier League champions Arsenal ahead of the 2026/27 season.
Ipswich Town have bolstered their squad ahead of their Premier League return by completing the signing of Ghana winger Abdul Fatawu from Leicester City.
