Brown, 23, is yet to play Premiership football for the Royals after breaking his ankle in pre-season 12 months ago.
He joined from Tamworth in 2005 and the club have decided to take up the option of another year on that contract after a wasted year through injury.
Director of football Nicky Hammond said: "His attitude's been fantastic. We're taking the option to give him the opportunity to show what he can do."
Brown had a three-month spell on loan at Bournemouth at the end of the 2005/06 season before breaking his ankle later that year.
Hammond added: "Aaron has worked tremendously hard to overcome a really bad break."
BBC