He rejected a move to West Ham last week, with Tottenham and Liverpool also chasing his signature.
Spurs have had a £13m bid turned down, and Varney insists Bent will be lining up in the season opener against Scunthorpe on August 11 if no-one matches their asking price.
"We've a valuation and we will not sell for less than that, other bids have not met our valuation," said Varney in the South London Press.
"West Ham matched our valuation and that was why they were given permission last week to speak to Darren.
"No other club has managed that and as things stand Darren will be staying with Charlton. He is our player and under contract to us."