Newcastle have had an agreement with Chelsea since the summer but the 21-year-old was only allowed to move on the condition that the Blues found a replacement at left wing-back.
The deal will be an initial six-month loan deal and the former Fluminense player will conduct a medical in the next 24 hours.
Kenedy has made only five appearances this season and his only loan move since joining Chelsea was an unsuccessful spell with Watford that was cut-short by injury.
Emerson will be that replacement as Antonio Conte looks for competition for Marcos Alonso while Rafael Benitez will get his first signing of the January transfer window.
Chelsea are also talking with Roma for Emerson's team-mate Edin Dzeko as the Serie A club admit that they are prepared to lose the duo in January.
Sevilla remain interested in a loan move for Michy Batshuayi, who is similarly only allowed to move if a replacement is signed, while Charly Musonda is in talks with a number of clubs in England and abroad.