Paul Onuachu, a striker for the Super Eagles, has moved from Genk to permanently join Southampton.
Onuachu has committed to the Premier League team for three and a half years.
The South Coast club beat Bundesliga side, Eintracht Frankfurt to the forward.
Southampton manager Nathan Jones said: “Paul is a significant signing for us and completes what has been an extremely positive month in terms of recruitment.
“He’s a handful to play against, has got a tremendous record throughout his career and he’s also someone who brings great experience with him, so he’ll be a really positive addition to the squad.”
Onuachu has a strong reputation entering the St Mary's Stadium after scoring 17 goals in 22 games for Genk this season.
He left the club with a total of 85 goals in 134 appearances after joining in 2019 from the Danish team FC Midtjylland.