Weydandt, who left the seventh tier to sign for fourth-division outfit Germania Egestorf four years ago, joined the Hanover reserve team in the close-season, but caught the eye of coach Andre Breitenreiter in training and was drafted into the senior side.
He scored twice on his debut as a substitute in a 6-0 German Cup thrashing of Karlsruher, before also finding the net in a 1-1 draw with Werder Bremen on the opening weekend of the league campaign, within a minute of coming off the bench.
And Hanover have now upgraded Weydandt's amateur deal to a professional one, after he was an unused substitute against Borussia Dortmund last Friday.
"I'm really excited about the opportunity I'm getting," he told the Hanover website.
"I've been well received -- by the coaching and support staff and by every single player. I really appreciate that."
His career holds similarities to that of England international and former Premier League winner Jamie Vardy, and Hanover sporting director Horst Heldt said his story was a "fairytale".
"'Henne' has absolutely earned his 'promotion' with his strong performances in training, which he has impressively backed up in his first two competitive matches," added Heldt.