The European Parliament has voted in favour of a resolution by Irish MEPs, calling for the release of Ibrahim Halawa from jail.
Over 560 MEPs voted overwhelmingly in favour of the resolution, while 11 voted against.
The resolution stated that Mr Halawa could face the death penalty.
Just before the vote, his two sisters received a round of applause from MEPs when they were introduced to the parliament by Sinn Féin MEP Lynn Boylan.
The family of the 20-year-old, who has spent the past three years imprisoned in Cairo following his arrest during protests in the Egyptian capital in 2013, has welcomed the support of Europe's parliamentarians.
His trial was postponed for the tenth time this week and has been rescheduled for this Saturday.
Seven Irish MEPs addressed the parliament ahead of the vote, commending Ms Boylan for her work on bringing the resolution to this stage.
Earlier, Ms Boylan said she expects the motion to pass as it already has support from seven of eight political groupings in the parliament.
Speaking on RTÉ's Morning Ireland, she said while the matter of whether Mr Halawa is freed is up to the Egyptian authorities, the motion will give his case prominence at EU level.
Ms Boylan called on EU bodies to monitor his trial.
She said the situation is untenable and such a resolution would send a strong message to Egypt.
Halawa case raised in Dáil
Minister for Foreign Affairs Charlie Flanagan has said the Government would take all appropriate action to secure the release of Mr Halawa.
The issue was raised by Sinn Féin TD Sean Crowe and Anti Austerity Alliance TD Paul Murphy during Minister's Questions in the Dáil this morning.
Mr Flanagan said the Government's firm diplomatic approach was in his best interests.
He said he noted the debate today in the European Parliament and said he has specifically raised the case with High Commissioner Federica Mogherini.
He said the EU remained supportive of the Government's approach.
Mr Crowe said the Egyptian embassy was briefing TDs, senators and MEPs in relation to the case and he asked the minister if he was concerned at some of the information coming from these briefings, including an assertion that he had addressed the court during his hunger strike, which Mr Crowe said had not happened.
He added that there was an assertion this was not a mass trial.
Mr Flanagan said he was aware not everyone agreed with the Government's stance, but he urged caution against doing anything that would hinder his case.
Mr Murphy said Ibrahim Halawa had spent three birthdays in prison and his trial had been postponed ten times.
He said while the Government could not wave a magic wand and get him out of prison, it was time for it to be louder and more clear about its absolute outrage.
Mr Flanagan said the Government approach was the best one.