Boutar, head of Mosaique FM, was arrested earlier this month in what the SNJT journalists' union called an attempt to "intimidate" the media.
Boutar was one of 10 public figures arrested within a few days, mainly critics of Saied, and also including members of the Islamist-inspired Ennahdha party.
The radio chief was questioned over the station's editorial line but then charged for "money laundering and illegal enrichment", his lawyers told reporters on Wednesday.
"These accusations are not based on any evidence or linked to any actual crimes," said lawyer Ayoub Ghdamssi. "This is a political case par excellence."
Ghdamssi said Boutar's arrest was in retaliation for Mosaique FM's flagship news debate program Midi-Show, "which upsets the authorities and poses them a problem by hosting free voices who believe in freedom of expression".
Mosaique FM is the most popular radio station in the North African nation and has long been critical of successive Tunisian governments, including that of President Kais Saied who staged a dramatic July 2021 power grab in the birthplace of the Arab Spring.
Saied has accused those arrested in recent days of "terrorism" and "plotting against state security" as well as being behind repeated food shortages.
Following this month's wave of arrests, Amnesty International said authorities were "escalating efforts to crack down on high-profile critics and perceived opponents" of Saied, urging the government to end what it called a "politically motivated witch hunt."