Friedel has started every league fixture for four seasons and made his 300th league appearance against Everton this weekend.
He also holds the Rovers record for the most Premiership appearances.
"I'm delighted to have extended the agreement by a further 12 months. It was not a difficult decision to make," he told the club website.
"Blackburn Rovers is home to me. This is my club and I have a special affinity with it.
"When you sign with a club, you always hope that it will turn out to be long term and that has certainly proved true for me here."