Weidenfeller, who will turn 37 in August, has been at the club since 2002 and is second only to sporting director Michael Zorc in Bundesliga appearances for the club having featured in 347 top-flight matches for Die Schwarzgelben.
He missed just three games over the two seasons that Dortmund won back-to-back Bundesliga titles under Jürgen Klopp between 2010 and 2012, but has played just eight top-flight encounters since Roman Bürki's arrival at the SIGNAL IDUNA PARK in summer 2015.
Weidenfeller insisted playing back-up to the Switzerland international was now his most important role.
"I have decided on a further year with my club and would like to support Roman Bürki in his development, and so help a young goalkeeper grow. I would like to soak up every last emotitional moment in black-and-yellow and I would like that to start on 27 May in Berlin."
The DFB Cup final against Frankfurt later this month could mark the start of a fitting 12-month swansong for Weidenfeller, adding another trophy to a well-stocked collection that includes a 2014 FIFA World Cup winner's medal.
Zorc: 'Club icon'
Should he play in Berlin's Olympiastadion, it would only be his third appearance in the competition this term, though without his penalty shoot-out heroics against Union Berlin in the second round, BVB might not have made it that far.
"Roman Weidenfeller is not only a club icon whose experience does us good, but he remains a good goalkeeper in top shape," said Zorc.
"Roman has been a key component of the BVB family for well over a decade. We are very pleased he wants to be between the posts for BVB for another year, and we will do our utmost to ensure that this loyal player, who has a strong presence, will have another function at the club after his career."