The defender is highly rated, but unfortunately for him Rafa Benitez has elected to go for a different type of player, and his progress at St James' Park had faltered.
He has signed for Porto on a four-year deal, keeping him at the club until June 2022.
"I will give everything for this shirt," Mbemba said in his first press conference.
"I am very happy. Everybody knows Porto, a great club."
Mbemba was born in the Democratic Republic of Congo, before spending many of his youth years in Belgium - he signed for Newcastle from Anderlecht.
The move should free up some money for Benitez to bring in a replacement, with Fabian Schär tipped to sign from Deportivo.