Ms Creagh helped to evacuate people from Westminster tube station as the horror unfolded on March 22 this year.
She was given lifelong membership of the Transport Salaried Staffs’ Association (TSSA) in honour of her actions.
Manuel Cortes, general secretary of the TSSA, presented her with the award at Wakefield Westgate Railway Station on Friday.
He said: “Mary displayed incredible courage during the recent Westminster terror attack.
“She realised that MPs had been evacuated from the Palace of Westminster, however the tube was still running and people were being allowed to walk into a danger zone.
“Mary took it upon herself to contact the control room of Westminster tube station and as a result passengers and our members were evacuated and taken out of harm’s way.”
The Palace of Westminster’s evacuation and lockdown procedures kicked in as the attack, which killed four and injured fifty, unfolded.
Ms Creagh found herself directed through a private tunnel into Westminster tube station as parliamentary security guards shouted: “Get out, we are under attack.”
She said: “When we ran out of parliament and into the tube station, I saw this woman pushing a pram.
“The contrast of her and her baby walking around metres from this incident just jarred me.
“I thought I have to get her and everyone else to safety but I can’t do that by myself.”
Ms Creagh raised the alarm with station workers, who put their security procedures in place to prevent passengers walking into the attack zone.
Her gesture prompted widespread praise, including from a retired Leeds headteacher, whose daughter was travelling on the tube towards Westminster at the time of the attack but was halted from going further.
The TSSA’s honour, presented in its 120th anniversary week, is the highest the union can bestow.
Its executive committee voted unanimously to give Ms Creagh the award.
Accepting the honour, she said: “I still pay tribute to the way that the staff at Westminster tube handled my slightly garbled request to shut the station - all credit to them.
“Our thoughts also remain with the victims of the attack and with their loved ones.”