The Newcastle United owner has close to a nine per cent stake in the Ibrox club, and Sports Direct has control of their retail operations.
“We can confirm that officers carried out a search of a property in Derbyshire,” Police Scotland said.
“As this is part of a live inquiry, it would be inappropriate to comment further.”
A statement from the sportswear firm read: “The premises of Sports Direct at Shirebrook were visited by Police Scotland conducting an investigation relating to Glasgow Rangers FC and various persons previously employed by and or associated with Rangers.
“The police investigation is not directed at Sports Direct or at any of its directors or employees. The police were seeking documentation which might assist the investigation.
“Sports Direct has co-operated fully and will continue to co-operate in the provision of information that the police request.”
Sports Direct’s merchandising deal with Rangers began in 2012 and Ashley also acquired the naming rights to Ibrox Stadium.
His influence grew with a series of loans and the placing of former Newcastle managing director Derek Llambias and Sports Direct executive Barry Leach on the board.
They were both voted off as a new regime swept to power in March.
Last month, Rangers were fined £5,500 by the Scottish Football Association after charging the club with two offences relating to Ashley’s involvement with them.
The club have admitted that a previous board contravened regulations relating to dual ownership.
Ashley’s involvement began after Charles Green’s consortium took control at Ibrox in June 2012, after which the Glasgow club re-emerged in the bottom tier of Scottish football.
Previous owner Craig Whyte was arrested with four others last year in the ongoing police investigation into his acquisition of the club from Sir David Murray in May 2011. The club went into administration in February the following year.
Whyte was released on bail on 28 November after appearing in Glasgow Sheriff Court charged with fraud.