Singler was taken by the Pistons with the No. 33 pick in the draft. He's been playing with Spanish team Lucentum Alicante during the NBA lockout.
Alicante says it has agreed to sell Singler's rights to Real Madrid. The club says the forward will join Madrid once the NBA lockout is officially over.
Singler will play for Alicante on Sunday before signing with his new team on Monday after medical tests. Financial details were not released.
Singler joined Alicante in August and has been the league's top rookie, averaging 15 points.
The Pistons retain Singler's NBA rights while he is playing overseas.
Information from The Associated Press was used in this report.