The DR Congo international moved to the Hillsborough Stadium on a free transfer, thus becoming the Owl’s fourth signing after Nigeria’s Fisayo Dele-Bashiru, Chey Dunkley and Izzy Brown.
Kachunga starred for Huddersfield last season, scoring three times in 36 league games as the Terriers finished 18th on a log of 24 teams.
Having teamed up with Sheffield, the 28-year-old would be hoping to help Garry Monk men’s ambition of securing a promotion ticket to the Premier League.
An enchanted Kachunga took to social media to express his happiness with his new adventure.
“Excited to start my new adventure at Sheffield Wednesday. Looking forward to the new season and meeting all the fans!” he posted on Twitter.
He is expected to make his debut when Monk's team face Walsall on Saturday, September 9 in a League Cup encounter.
After two seasons at the Benteler-Arena, he moved to FC Ingolstadt in 2015 for a club-record transfer fee of €1.7 million. There, he signed a season-long loan deal with an option to buy at the end with Huddersfield Town in June 2016.
Delighted by his performances in his debut campaign, Huddersfield paid Ingolstadt £1.1 million to turn Kachunga's loan deal into a permanent transfer.
On the international scene, he represented Germany at U19 and U21 levels before opting out to represent DR Congo at senior level. His only cap came in a 2-1 friendly defeat to Kenya on 26 March, 2017.