Police on Sunday said the Eagle S oil tanker was being released from custody.
According to the police, investigations led by the National Bureau of Investigation (NBI) had reached a point where there were no longer grounds to continue detaining the tanker.
"As far as the criminal investigation is concerned, the tanker is not prevented from continuing its passage to leave Finland's territorial waters," the police said in a statement on Sunday.
The Cook Islands-flagged vessel is suspected of involvement in subsea cable damage last December. The ship is thought to be part of Russia's "shadow fleet" of sanctions-busting oil tankers.
Finnish Customs determined the unleaded gasoline and diesel on board the vessel to be subject to Russian sanctions.
The Finnish Border Guard supervised the vessel's departure from Finland's territorial waters and exclusive economic zone.
Eight suspects
The preliminary investigation has identified eight criminal suspects in connection with the cable-damaging incident. Three individuals remain subject to travel bans, while restrictions on five others were lifted earlier this week.
Police stated that the criminal investigation is ongoing, including additional interviews with the crew and further analysis of the collected material.
Offences under investigation include aggravated criminal mischief and aggravated interference with communications. The investigation is expected to be concluded by the end of April.
Finnish grid operator Fingrid and Estonian operator Elering also cancelled demands to seize the ship, saying the financial risks associated with maintaining the vessel would likely exceed its value.
Fingrid and Elering have said they plan to file a lawsuit against the Eagle S for the damages caused and seek compensation through legal proceedings.
The Eagle S is suspected of intentionally damaging subsea electricity and telecom cables in the Gulf of Finland on Christmas Day, leaving behind a 100-kilometre-long trail gouged into the seabed.