RSF said it ranked Tunisia a lowly 121 out of 180 countries worldwide in the annual index published on Wednesday to mark World Press Freedom Day as a result of Saied’s "growing authoritarianism and inability to tolerate media criticism".
It marked a sharp decline in press freedoms in Tunisia which enjoyed a good spell after uprisings overthrew the dictatorship of Zine El Abedine Ben Ali in 2011.
Hard-fought gains since Ben Ali's demise had meant that Tunisia led the way for press freedoms in the Middle East and North Africa for years - but Saied seems set on reversing these, RSF said.
Since Saied seized a host of powers in a July 2021 coup, Tunisia has tumbled in the World Press Freedom rankings, falling over 50 places.
Concerns for press freedom have only increased since Noureddine Boutar, head of Tunisia's main independent news outlet Mosaique FM, was arrested at his home in February.
Boutar was accused by a judge of "harming the highest echelon of authority and symbols of the state", the Committee to Protect Journalists said at the time.
He faces money laundering and "illicit enrichment" charges, but his detention has been denounced as an attempt to intimidate journalists critical of the government.
Countries in the Middle East and North Africa make up eight of the 15 worst-ranked offenders in the entire global index.
"The very low score of some countries, including Syria (175th), Yemen (168th) and Iraq (167th), is due in particular to the large number of journalists who are missing or held hostage," said RSF.