CEO of Mangalam TV channel R Ajit Kumar and media persons S V Pradeep, M B Santhosh, Feroz Muhammed and Jayachandran were arrested by the special investigation team after questioning them for hours.
They would be produced before a court tomorrow, police said.
Four other persons, named in the FIR, were also questioned but were let off, police said.
Yesterday, Kerala High Court had rejected the anticipatory bail plea of the nine accused.
The channel on its opening day on March 26 aired an audio clip of the purported talk of Transport Minister A K Saseendran, NCP representative in the LDF cabinet, with a woman, following which he had resigned the same day.
The TV channel had tendered an apology for airing the contents and admitted that it was a "sting operation" involving one of their women journalists and not a housewife, as it had claimed earlier.