Nazanin Zaghari-Ratcliffe was detained in Iran for nearly six years after being arrested while taking her daughter to see her family.
She was accused of plotting to overthrow the Iranian government, which she denied.
Labour's Tulip Siddiq, the family's local MP, tweeted an image of Mrs Zaghari-Ratcliffe this afternoon, wearing a yellow top and a grey scarf, smiling on the window seat of a plane.
"It's been 6 long years - and I can't believe I can FINALLY share this photo," Ms Siddiq wrote.
"Nazanin is now in the air flying away from 6 years of hell in Iran.
"My heart goes out to Gabriella and Richard, as her long journey back home to them gets closer by the minute. #NazaninIsFree"
Here's a timeline of Nazanin's detention in Iran.
April 2016
Nazanin is detained by the Iranian Revolutionary Guard at Tehran airport after visiting Iran to introduce her daughter Gabriella to her parents.
September 2016
Richard Ratcliffe says his wife has been jailed for five years following a conviction on unspecified “national security-related” offences.
November 2017
Boris Johnson tells MPs that Nazanin was working in Tehran training journalists at the time of her arrest. Four days later, she was summoned before an unscheduled court hearing, where his comments were cited as proof that she was engaged in “propaganda against the regime”.
A Foreign Office spokesman says Mr Johnson accepted he “could have been clearer”.
November 2017
Ratcliffe says his wife has seen a medical specialist after finding lumps on her breasts and is “on the verge of a nervous breakdown”.
May 2018
Ratcliffe says his wife has been told to expect another conviction after appearing in court over a new “invented” charge.
August 2018
Nazanin is given temporary release from prison for three days and her husband says it feels like “home is one step closer”. She returns to prison three days later.
October 2019
The couple’s daughter Gabriella returns to the UK after more than three years living with her maternal grandparents in Tehran.
January 2020
Richard Ratcliffe and their then five-year-old daughter Gabriella meet the PM in Downing Street, but Ratcliffe says there was “no breakthrough”.
March 2020
Nazanin is temporarily freed from jail due to the Covid pandemic and can only go within 300 metres of her parents’ home. The family are able to talk via video calls for several hours a day.
March 2021
On the day Nazanin’s sentence is due to come to an end, her MP reveals she has faces a new court date. The following month she is given another one-year jail term and banned from leaving Iran for a year.
May 2021
Iranian state TV claims Britain will pay the £400 million debt relating to a cancelled order for 1,500 Chieftain tanks dating back to the 1970s, paving the way for Nazanin’s release.
November 2021
Ratcliffe ends a 21-day hunger strike outside the Foreign Office.
March 2022
Nazanin’s MP says her constituent has had her British passport returned and a team of officials are in Tehran to negotiate. Hours later Tulip Siddiq announces that she is at Tehran airport and on her way home.
