"Chelsea Football Club and Bayer Leverkusen have reached an agreement for the transfer of Andre Schürrle subject to the completion of legal documentation and related matters, including personal terms and passing a medical," the Londoners said in a statement.
The transfer fee was not disclosed but media reports have put it at 18 million pounds.
German international Schürrle scored 11 Bundesliga goals last season.
The signing of Schürrle could mean that fellow German Marko Marin, a disappointment since joining Chelsea from Werder Bremen 12 months ago or Victor Moses could be heading for the Stamford Bridge exit door.
"I need to work with the players and not commit injustice," the 50-year-old Portuguese said on Monday.
"I need to give them a chance, be fair with them. After that we'll have time to make decisions."
Leverkusen have acted quickly to bring in Schürrle's replacement - 20-year-old South Korea international Son Heung-min.
