Nikolaos Karvounakis, 35, who is a Greek National, pled guilty to being in possession of items for a terrorist purpose at the High Court in Edinburgh today - Wednesday, January 19.
The IED was discovered in a public shelter in Princes Street Gardens on January 11, 2018.
Army bomb disposal experts carried out a controlled explosion at the scene, roughly three hours after the alarm was raised. No one was hurt during the incident.
Police Scotland have welcomed the conviction of Karvounakis.
Detective Chief Superintendent Stuart Houston said:“Karvounakis showed a blatant disregard for members of the public by placing the IED indiscriminately within Princes Street Gardens. Fortunately, it did not initiate, but his intention was clear and there was certainly the potential to cause significant, or even fatal, injury to innocent passers-by.
“I welcome his guilty plea and conviction which is testament to the perseverance of our diligent investigation team over the last four years.
“Since the discovery of the package, officers from Police Scotland’s Counter Terrorism Unit carried out extensive enquiries, including with European partners and law enforcement agencies. They were absolutely committed to the challenging inquiry to identify who was responsible.
"The successful conclusion of this investigation today has been founded on the strong co-operation and working closely with the Counter Terrorism Network across the UK and internationally."
Sentencing will reportedly take place next month.