But he has rejected a move to the Hammers, who now expect the former Ipswich player to start the season playing for them in the second tier of English football.
"We set a valuation for Darren and West Ham were the only club prepared to meet that," said Charlton chief executive Peter Varney.
"We gave them permission to speak to Darren, which he did, and he has decided not to join West Ham.
"We look forward to Darren starting with us in the Championship next season, which is a massive boost to our chances of returning to the Premier League."
Charlton were relegated from the Premier League last season, and will open their season by hosting Scunthorpe on Saturday August 11.