The new deal will keep the 23-year-old at Reading until the summer of 2012.
Long told the club website: “This is my sixth season at the club and I’ve enjoyed every year here.
“It’s nice that the manager [Brian McDermott] has shown some faith in me and offered me a new deal.”
Long added: “I’ve had ups and downs here but mostly ups since the manager has been here, but I was delighted to snap up the deal when I got the chance.”