Addison boarded a plane Tuesday on the first leg of her journey back to Oregon.
"I am thrilled to report that Dr. Stacey Addison has gotten her passport back, and is now on a plane returning home here to Oregon," Sen. Jeff Merkley (D-Oregon) said. "This is terrific news for Stacey, for her family, and for all the Oregonians who have followed Stacey's story and helped support her from afar," Merkley said in a statement.
Addison, 41, was detained in September in the small Southeast Asian nation in a drug case in which she says she's innocent
She was released in December but she still couldn't leave because her passport -- seized during the investigation -- had not been returned.
Former East Timorese President and Nobel Peace Prize laureate Jose Ramos-Horta, hosted her temporarily at his home.
Addison's arrest in September was an unexpected bump in what had been a multi-year trip around the world.
She said she had been traveling solo since January 2013, having quit her job as a veterinarian to explore the globe. On September 5, she was sharing a cab from near the Indonesian border to the East Timor capital of Dili.
On the way, a fellow passenger asked to stop to pick up a package at a DHL office, her mother, Bernadette Kero of Oregon, has told CNN. After the man picked up the package, police surrounded the car and arrested the occupants, according to Kero.
The package was found to contain methamphetamine, Addison has said.
She initially was held for four nights, and a judge released her -- but prevented her from leaving the country while the case was still being investigated -- after the man testified that he didn't know her, Kero said.
In late October, during a court appearance where she thought she'd retrieve her passport, a judge ordered her arrest again and sent her to Gleno prison outside Dili.
Paul Remedios, a lawyer representing Addison, said at the time that the court detained her again because there was a warrant for her arrest, and that the reason for the warrant was unclear.
Kero told CNN in November that the case was a "nightmare."