Brazilian striker Oliveira returns to Betis
Betis paid 8,977,142 euros ($11.8 million) including commissions for 50 percent of the player's rights, the club detailed in a statement on their website.
They said they had an agreement with Oliverira until 2013, and that the player would arrive in Seville on Sunday.
The 28-year-old former Brazilian international was Betis's top scorer in the 2004-5 season with 22 goals but was sold to AC Milan for 17 million euros in 2006.
After a disappointing spell in Serie A, he returned to Spain in 2007 with Zaragoza. He top-scored for Zaragoza in with 17 goals but could not prevent them being relegated to the second division last season.
Betis are struggling in 16th place in the Primera Liga and host Getafe on Sunday.