The 42-year-old, identified by German authorities only as Sami A and by Tunis as Sami Idoudi, had lived in Germany for more than two decades, but outrage over his presence grew in recent months as Germany cracks down on failed asylum seekers.
"I can confirm that Sami A was sent back to Tunisia this morning and handed over to Tunisian authorities," interior ministry spokeswoman Annegret Korff told reporters, following a report in the top-selling Bild newspaper.
"He was placed under arrest just after his arrival in Tunis," a spokesman for the Tunisian anti-terror force, Sofiene Sliti, told AFP.
Sami A had previously successfully argued against his deportation, saying he risked being tortured in his homeland.
A court in the city of Gelsenkirchen ruled against the deportation late yesterday, upholding the assessment that the suspect potentially faced "torture and inhumane treatment".
Considered a security threat over his suspected ties to Islamist groups, Sami A has for years had to report to police but was never charged with an offence.
Judges in a 2015 terror case in the German city of Muenster however said they believed Sami A underwent military training at an Al-Qaeda camp in Afghanistan in 1999 and 2000 and belonged to bin Laden's team of guards.
German authorities first rejected Sami A's asylum request in 2007 but prosecutors' efforts to expel him were repeatedly blocked by courts citing the danger of torture in Tunisia.
An unrelated court ruling last month involving another Tunisian man -- accused over a 2015 attack on Tunis' Bardo museum -- helped pave the way for Sami A's expulsion.
Germany's hardline interior minister, Horst Seehofer, seized on the precedent to say he hoped Sami A would be next, calling on migration officers to make the case "a priority".
Bild led a vocal campaign against Sami A's presence in Germany, with revelations that he collects nearly 1,200 euros (USD 1,400) a month in welfare sparking particular outrage.
Sami A has a wife and children who are German citizens.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)