The two series, run as separate championships in the past, will now both be organised by Dorna, at the instigation of hedge fund Bridgepoint.
The Federation Internationale de Motocyclisme welcomed the move, and said it would sit down with all stakeholders in order to reposition the two championships.
FIM president Vito Ippolito said: "I welcome Bridgepoint's decision to bring the two championships together within a single organisation.
"We shall shortly be holding a meeting of all the stakeholders in order to reposition the two championships and look into the technical and operational implications.
"We shall then be able to adapt the regulations to ensure that they have a distinct identity in future."
The FIM acts as governing body to 50 motorcycle world championship events, including MotoGP and WSBK.