Kabak spent the second half of last season with the Reds on loan from Schalke, making 13 appearances and becoming a popular figure among supporters.
The club had agreed an option to buy with the Bundesliga club, but opted to allow him to return to Gelsenkirchen as they pushed for the £36 million signing of Ibrahima Konate instead.
Norwich confirmed the deal on Monday evening, with the Turk able to then join the Canaries on a permanent transfer worth £11.1 million next summer.
It could be, then, that Kabak starts against Liverpool in that tie, with Farke welcoming a player “full of potential with a great reputation.”
“He’s already had a taste of Premier League football at Liverpool, which says a lot about his potential. He’s also a great character.
“We want to help him reach his very best levels. We know he is capable to shine for us and improve a lot. We are really happy that we are able to do this piece of business.”