The Magpies have been strongly linked with the 23-year-old, who is out of contract at the end of the season, and the player himself has spoken about his interest in a move to the north-east.
And the Toulouse website has now released a statement which read: "Moussa Sissoko has agreed with Newcastle United for a definitive transfer, that takes effect today.
"All the club wishes him continued success in his career."
However, when asked to comment on this development, Newcastle said they had nothing new to add regarding the situation.
Sissoko has told L'Equipe: "Newcastle is a club that attracts me, even if they do not have a good ranking currently.
"I trust that group, considering what they achieved last season. Moreover, the officials have invested a lot on quality French players. They will have better results in the second part of the season.
"All those Frenchman are reassuring. I know them well and that would help me to adapt."
The Magpies have been active in the transfer market and this week they have already completed the signings of two Frenchmen in the shape of defender Mapou Yanga-Mbiwa and forward Yoan Gouffran.
Sissoko was actually suspended by Toulouse earlier in the week, due to his desire to force a move away from the club he has been at since 2003.