Arsenal have been chasing him for some time now, but confirmed on Monday – after a hastily-deleted confirmation tweet from Anderlecht – that they had got their man.
The club also confirmed Lokonga will wear the number 23 shirt – made vacant by David Luiz following his departure from the club.
In a statement, Arteta said: “Albert is a very intelligent player who has shown great maturity in his performances during his development. He has been coached well by Vincent Kompany and his team at Anderlecht.
“I know Vincent very well and he talks so highly about Albert and the positive impact he had to Anderlecht in recent seasons.