Kenedy has completed his loan move from Chelsea to Newcastle.
The move will give Kenedy, 21, the chance to play first-team football for the remainder of the campaign as his chances at Chelsea have been limited.
He will also be reunited with Christian Atsu, who was sold by Chelsea to Newcastle last summer after impressing while on loan.
Newcastle boss Rafael Benitez came close to signing Kenedy during the summer transfer window and remained interested.
“I’m so happy with this opportunity at Newcastle,” Kenedy told the Magpies’ website.
“They’ve opened the door to me to come here, show my potential and come and play for Newcastle.
“It’s a traditional club and Rafa Benítez is a fantastic, amazing coach.
“Christian Atsu, as well – we trained together at Chelsea and know each other, and he said good things about the club. So it was easy to take this decision.”
Kenedy has not featured in the Premier League this season, with all five of his appearances for Chelsea coming in cup competitions.
“For sure we are talking about a young player with great potential,” said Blues boss Antonio Conte.
“At this moment in his career he needs to play with regularity and I think going to Newcastle is a great challenge for him.”
Conte hopes Kenedy can follow the example of defender Andreas Christensen, who has established himself as a first-team player at Chelsea after spending two seasons on loan at Borussia Mönchengladbach.
The Italian also believes Kenedy is better equipped for Premier League football than during his unsuccessful spell at Watford last season.
He barely featured after joining the Hornets on a season-long loan and therefore returned to Chelsea last January.
Conte said: “I think this way is good for the club and we have used the same way for Christensen. Now Christensen is a Chelsea player who is always in the starting 11.
“I think it will be good for Kenedy but at the same time he has to know that he must be ready to fight to play at Newcastle, because don’t forget in his first six months at Watford he struggled a lot to play and played only 24 minutes.
“But I think now he is more ready. Now he can show his potential by going out on loan.”
Meanwhile, Alvaro Morata and Cesc Fabregas have been ruled out of Chelsea’s Carabao Cup semi-final second leg at Arsenal.