The British-Iranian mother has been imprisoned in the country’s capital, Tehran, for almost two years after being arrested during a family holiday.
Mr Johnson provoked outcry last month after telling a parliamentary select committee that the Ms Zaghari-Ratcliffe had been “training journalists” in Iran – a claim that could lead to her jail term being doubled to 10 years. In reality, she was visiting family in the country.
The visit would mark Mr Johnson’s first to Iran since taking over as Foreign Secretary last year. He is likely to meet with senior government officials, including the country’s foreign minister, Javad Zarif, and will attempt to secure the British woman’s release.
However, a swift resolution to the saga is unlikely, because Iran has refused to recognise Ms Zaghari-Ratcliffe’s British citizenship and is treating her as an Iranian.
Her husband, Richard Ratcliffe, has warned that she is suffering from depression, insomnia and panic attacks. She is also said to have been "periodically suicidal".
Commenting on news of Mr Johnson’s trip, Amnesty International UK’s director, Kate Allen, said: “We’re cautiously hopeful that this could be the light at the end of the tunnel for Ms Zaghari-Ratcliffe.
“As we’ve been saying over and over, Ms Zaghari-Ratcliffe is a charity worker who’s been jailed for five years after enduring solitary confinement and a deeply unfair trial.
“The Iranian authorities have a record of toying with the fate of prisoners being held for ‘political’ reasons, so it’s still very hard to feel confident that her release is imminent.
“We fervently hope the Foreign Secretary’s visit can secure her speedy release, but if it doesn’t we’ll go on campaigning. This is a gross injustice and it must be set right.”