Mrs Zaghari-Ratcliffe has worked for the Thomson Reuters Foundation and the BBC, but insisted the 2016 visit was for her daughter to meet her grandparents.
Mr Johnson was appearing before MPs on the House of Commons Foreign Affairs Select Committee on 1 November, criticised Iran over the case before saying: “When I look at what Nazanin Zaghari-Ratcliffe was doing, she was simply teaching people journalism as I understand it.
“[Neither] Nazanin Zaghari-Ratcliffe nor her family has been informed about what crime she has actually committed. And that I find extraordinary, incredible.”
Four days later, Mrs Zaghari-Ratcliffe was summoned to court where the foreign secretary’s comments were cited as evidence against her.
At this hearing she was accused of engaging in “propaganda against the regime”.
The Iranian judiciary’s High Council for Human Rights said Mr Johnson’s comments “shed new light” on the charity worker and proved Mrs Zaghari-Ratcliffe “had visited the country for anything but a holiday”.
Monique Villa, chief executive of the Thomson Reuters Foundation, called on Mr Johnson to “immediately correct the serious mistake he made”.
Ms Villa said there was a “direct correlation” between Mr Johnson’s comments and the unscheduled court appearance.
“This accusation from Judge Salavati can only worsen her sentence. She is obviously a bargaining chip between the UK government and Iran and this injustice must stop as soon as possible.
“Whatever is at stake should be paid attention to by the UK government.”