The club confirmed the news on Twitter on Friday:
Reus, 28, has been at Dortmund since 2012.
He has endured numerous fitness woes during his time at the Westfalenstadion and only returned from an eight-month layoff in February.
The German has wasted no time in re-establishing himself as one of BVB's most talented attacking players, as he has netted three times in his last three Bundesliga appearances.
Per Squawka, his stats show that, when fit, there is arguably no better player in the Dortmund side:
It is a big boost for Dortmund that Reus has committed his future to the club until 2023. His previous deal was set to expire in 2019.
Reus' aim for the remainder of the 2017-18 season is likely to stay fit and help Dortmund in their bid to finish in the Bundesliga's top four and potentially win the UEFA Europa League.
There is also the small matter of the 2018 FIFA World Cup coming up in the summer, and a fit and in-form Reus will surely warrant a spot in Joachim Low's Germany squad for the Russia tournament.