No details of today's meeting were immediately available. He had been expected to discuss the fate of detained dual national, Nazanin Zaghari-Ratcliffe, who is serving a five- year prison sentence for allegedly plotting against Iran's government.
Her husband says she faces trial on new charges Sunday that carry the possibility of an additional 16-years imprisonment, but Iranian judiciary spokesman Gholamhosein Mohseni Ejehi said last month that her verdict has been finalised.
London is considering repaying Tehran some 400 million pounds from a pre-1979 arms deal. Both sides say the money isn't related to Zaghari-Ratcliffe.
Johnson met with Ali Akbar Salehi, the head of Iran's nuclear program, earlier Sunday.