The 24-year-old Germany international moved to Stamford Bridge from Werder Bremen last summer, but the capture of compatriot Andre Schurrle from Bayer Leverkusen means he has fallen down the pecking order under Jose Mourinho.
A statement on chelseafc.com read: "Chelsea Football Club and Sevilla Futbol Club have reached an agreement for the season-long loan of Marko Marin, subject to the completion of legal documentation and a medical."
Marin made 16 appearances for the Blues last term after a hamstring injury early in the season delayed his competitive debut.
Schurrle this week became Mourinho's first signing of his second spell as Blues boss, with more anticipated.
Following the departures of Ross Turnbull and Hilario and with Belgian Thibault Courtois on loan at Atletico Madrid for a third successive season, a back-up goalkeeper is required as a reserve for Petr Cech.
With only youngster Jamal Blackman in place, Chelsea have been linked with Norwich's England goalkeeper John Ruddy, who spent much of last season out injured with a thigh problem.
- Sports & Recreation
- Marko Marin
- Chelsea Football Club
- Jose Mourinho
- Andre Schurrle
- Bayer Leverkusen
- Werder Bremen