Pearce, who has previously played for Portsmouth (twice), Bournemouth, Peterborough and Leeds, helped Wigan to promotion from League 1 back into the Championship last season.
Henderson will remain in the Championship this season after signing for Nottingham Forest. Charlton have brought in Crofts though after the former Brighton mans trial spell.
Charlton`s first League side game jitters
League One side Charlton sign former Gillingham, Brighton and Norwich midfielder Andrew Crofts on a one-year deal.
Many are judging too soon
Manager Russell Slade has been delighted with the trip to Austria, especially as we took victory in the second friendly arranged for while we were out there.
With striker Tony Watt's future long being in doubt at The Valley, the club have today confirmed the speculation linking him with a move to Scottish side Hearts.
Former Celtic striker Tony Watt has returned to Scotland after sealing a season-long loan switch to Hearts.