The German was unveiled on Thursday by president Jose Maria del Nido and sporting director Ramon Rodriguez Verdejo 'Monchi' and declared he was attracted to the Andalusian club because of its illustrious history.
"Sevilla is a club of great tradition and I've come here to be a part of their next league campaign and put them back in the place they were several years ago," he said.
And the 24-year-old stressed he would not be content with playing a fringe role at the Sanchez Pizjuan.
"I hope to become a leader here," he said.
"After speaking with Monchi and (midfielder) Ivan Rakitic, who is a symbol of leadership at this club, I have got to know the club's philosophy and the project they have in mind."
Marin insisted that he had not joined Sevilla on the recommendation of Chelsea boss Jose Mourinho, but had been influenced by other players he knows who have played in Spain.
He said: "I spoke with many players and they told me that La Liga was one of the best leagues in the world, and I want to prove my worth here."