President Moncef Marzouki issued the stamp with an image of Zouhair Yahyaoui, the editor of TUNeZine, a website with satirical content that criticised the Ben Ali regime.
The stamp holds an image of "the late Zouhair Yahyaoui, pioneer of cyber-dissidence", the postal service said in a statement.
Marzouki personally appointed March 13 as the day to commemorate internet freedom as it was also the anniversary of Yahyaoui's death.
Whilst at TUNeZINE, Yahyaoui once invited readers to vote on whether Tunisia was "a republic, a kingdom, a zoo, or a prison."
Yahyaoui was imprisoned for 18 months for "propagating false news" and "thieving from an employer" by the Ben Ali regime.
During his prison sentence, he faced torture and wide-spread brutality - ultimately leading to his decision to undergo prolonged hunger strikes.
Yahyaoui suffered a heart attack after he was released from prison. His family claim the incredibly harsh conditions he faced in prison led to a serious deterioration in his health.
Widely considered to be one of the country's first online dissidents, Yahyaoui received the 2013 Barbara Goldsmith Freedom to Write Award for his courage in the face of adversity.
Translation: #Tunisia The postal service celebrates national #NetFreedom day and pays tribute to Zouhayer Yahyaoui! #13March