Jurgen Klopp's charges had gone four games without recording a victory in Germany's top flight before defeating bottom side Eintracht Braunschweig 2-1.
The poor run has severely hindered the club's chances of challenging for the title, though Dortmund remain firmly in the hunt for a UEFA Champions League spot.
Weidenfeller lamented another lacklustre performance from last season's Bundesliga runners-up, but believes the side can take confidence from the maximum haul.
"We know that we didn't play well," he told the club's official website. "But we can build on this win.
"We won, and that's what's important. Braunschweig gave their all to avoid to defeat.
"There are a few things we need to improve on. We still make mistakes or have lapses of concentration, and we will need to work on this."
A double from Pierre-Emerick Aubameyang either side of Benjamin Kessel's leveller was enough to secure the triumph for Dortmund and Weidenfeller paid tribute to the forward, while also hailing the return of centre-back Mats Hummels from an ankle injury sustained in November.
Weidenfeller added: "He (Aubameyang) is very important for us with his pace. It allows us to play long balls up the field.
"Mats is a vital part of the team. We were able to work the ball forward from the back much better."
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