The Addicks chiefs was honoured at the LMA's annual event in Old Billingsgate in London after leading the east London club to the third-tier title with a club-record 101 points.
Charlton lost only five league games all season, with Powell also picking up three manager of the month accolades over the course of the campaign.
The 42-year-old becomes the first Addicks boss to win a manager of the year award since Alan Curbishley in 2000.
Former Charlton boss Alan Pardew won the Premier League award for his work at Newcastle, with ex-Addicks striker and current Swindon manager Paolo Di Canio scooping the League Two award.







