Havard Nordtveit has joined Hoffenheim from West Ham for an undisclosed fee.
The Norway international heads back to Germany a year after arriving in London from Borussia Monchengladbach on a free transfer ahead of the 2016-17 season.
Nordtveit made 21 appearances in all competitions for West Ham, but has been deemed surplus to requirements at the London Stadium.
"I would like to thank Havard for his commitment and hard work last season," said West Ham manager Slaven Bilic.
"He is an excellent professional and we wish him all the very best at Hoffenheim."
Nordtveit spent the early part of his career in his native Norway before heading to Arsenal, where he had to rely on loan spells at Salamanca, Lillestrom and Nurnberg for first-team action.
The 26-year-old became an important member of the first team after earning a permanent move to the Bundesliga with Gladbach in 2011 and will hope to enjoy more success with a side who finished fourth in the top flight last season.