The 23-year-old Brazilian, who plays international football for Italy, completed a medical at Cobham on Tuesday.
Footballitalia has leaked a photo of Emerson holding up his new Chelsea jersey, donning the number 33.
He will provide competition and cover for current left-back Marcos Alonso. And because Emerson never featured for Roma in the Champions League, he will be able to play for Chelsea during their Round of 16 clash with Barcelona.
Emerson Palmieri completes transfer from #ASRoma to #ChelseaFC for reported €26m https://t.co/iNmymURc9p#CFCpic.twitter.com/HkAH6hWjob
— footballitalia (@footballitalia) January 30, 2018