The 36-year-old – who has become the youngest head coach in the Premier League – has been in dialogue with Town since his days with Bochum in 2016-17 after quickly being identified as a potential heir apparent to David Wagner.
Siewert was the subject of approaches from rival Bundesliga clubs during his subsequent time in charge at Borussia Dortmund II and spurned interest from Queens Park Rangers last summer.
The German insists that the trust and understanding built between himself and the club ensured that his decision was an easy one when Town got in touch following Wagner’s exit.
He said: “Since the beginning, when I was talking to Dean (Hoyle) and Julian (Winter), we had fantastic conversations.
“I know this club is special with a family side and that is why I trusted in them. That is why I wanted to take this opportunity.”
Despite obvious comparisons with Wagner, who also arrived at Town from Dortmund’s second team, Siewert is adamant he will prove his own man.
He added: “I always did it my way, so I cannot be compared to David Wagner because he is a fantastic manager. He had much success here, but now it is my new role, it is a new chapter.
“Of course there are similarities, because of our playing styles, but the most important thing is I am Jan Siewert and I have to do it my way and David his. I do not think you should compare the two.”
Town chief executive Julian Winter confirmed that the club spoke to no other candidate following Wagner’s departure from the club by mutual consent at the start of last week with Siewert always being No 1 choice.
He said: “We did not speak to anyone else. We kept a running list of candidates and Jan was always on that list and at the top.”
Siewert is ready for a new challenge: Page 24