According to L’Equipe, Marseille will pay €15m plus €5m add-ons for the Nigeria international.
Bamba Dieng will also move to Lorient as part of the deal.
Only a few details remain to be sorted before the transfer is concluded.
The Principality club beat OGC Nice and West Ham United to the service of the forward.
The 23-year-old has scored 12 goals in 18 league appearances for Lorient this season.