Aboubakar wil swap Ligue 1 for the Primeira Liga after scoring 17 goals for the Stade du Moustoir side in 38 games.
Porto have spent €3 million to secure 30 per cent of his economic rights. Previous star names such as Radamel Falcao and Hulk have also been acquired with the help of third parties.
The 22-year-old has penned a four-year deal at the Estadio do Dragao - his contract includes a €50m buy-out clause.
Hull City boss Steve Bruce had expressed an interest in Aboubakar as he looks to use the £12m received for Shane Long.
But the lure of Porto proved too strong, and Aboubakar will challenge the likes of Jackson Martinez and Leocisio Sami for a starting spot in coach Julen Lopetegui's side.
