Two of the people arrested are a player agent based in Monaco and his assistant who worked in Liege, Belgium.
RTBF report Henrotay was apprehended in Monaco, where he is now being held by the local police.
"The facts involve notably money-laundering operations and private corruption in the context of football player transfers", the prosecutor's office said in a statement. He was indicted by a Belgian judge who had travelled down to Monaco.
Authorities in Belgium have been conducting far reaching inquiries into suspected money laundering related to transfers in the country since earlier this year. His clients include Belgian internationals Thibaut Courtois, the Real Madrid goalkeeper, and winger Yannick Carrasco.
Prior to this, the website explain the renowned Belgian agent was already in a dispute after one of his former collaborators, Peter Smeets, accused Henrotay of pocketing a €6m commission from Youri Tielemans' transfer to Monaco, with Smeets filing a complaint about the issue.
It is understood that Newcastle believe they are not directly connected to the inquiry and as such are not part of the investigation.
The criminal probe adds to Anderlecht's woes on the pitch, where the 34-time Belgian champions are languishing a lowly 13th in the league with just a single win in their first six games this season.