Captain Philipp Sander is leaving Holstein Kiel for Borussia Mönchengladbach after leading them into the Bundesliga for the first time.
Kiel confirmed the transfer, reportedly via a release clause, after weeks of speculation. No financial details were given.
Midfielder Sander, 26, arrived in Kiel in 2015 and made his first team debut in 2018. His original contract was until 2027.
"It makes me extremely happy and proud that I can say say goodbye to Kiel as captain with such a successful and historic ending in the form of promotion," Sander said in a club statement.
Managing director for sport Carsten Wehlmann said: "Philipp Sander is a prime example for the path Holstein Kiel has been taking for many years."
Kiel were runners-up to St Pauli Hamburg in the second division season which ended on Sunday. Both are promoted, making Kiel the first club from Germany's northernmost state of Schleswig-Holstein to play in the top flight.
