Haniyeh spoke at a joint press conference with Johnston, who had arrived at his home at the Shati refugee camp in Gaza several hours after his release.
"If the Israelis think reasonably and rationally, and take into account the humanitarian issue and the suffering of the Palestinian prisoners, we will be able to reach a deal," the Hamas leader said.
He congratulated Johnston's family and his colleagues and said that "this is a happy moment for the Palestinian people."
Haniyeh, who had recently been given a cold shoulder by the international community following Hamas' takeover of Gaza, flaunted his new achievement, saying that Johnston's kidnapping was on the top of the Palestinian agenda since the first day.
He also said that Israel's actions were to blame for the delay in the efforts to release the reporter.
Haniyeh said that the negotiations for Johnston's release included talks between the Hamas leadership abroad and the British government. Hinting at the Palestinian emergency government operating in the West Bank, he said "I hope order, security, stability and the end of anarchy will also reach them."
He took advantage of the opportunity to turn to "our brothers in Ramallah," saying "if the intentions are good, we will be able to reach a dialogue and unity between us."
Johnston thanked the Hamas movement for releasing him and said that without Hamas' efforts, he would have stayed in captivity for a long time. He added that his abductors moved him twice during his time in captivity, which lasted close to four months.