Emily McLeod went to the aid of a 25-year-old who had been hit by a bottle and left bleeding from a head wound.
Despite the fact the man's attacker was still threatening to injure him, Emily pressed tissues to the man's head and waited with him for police to arrive.
The brave 15-year-old was left so shocked she didn't tell her mum what had happened.
But the Hyndland Secondary pupil came forward after reading a plea for information in the Evening Times.
Emily, who was 14 at the time of the May attack in Partick Station, said: "I was with my friend when I walked into the station and saw the man bleeding from his head.
"I just reacted really quickly. I knew he needed tissues for all the blood so I ran to a take-away and got napkins to press on to the wound.
"It was pretty scary because the attacker was still there and shouting at him. It was horrible seeing the man in so much pain."
The man received 17 stitches at the Western Infirmary and an investigation is continuing.
Emily, from Ruchill, was presented with a commendation award by British Transport Police Chief Constable Andrew Trotter at a ceremony in Glasgow City Chambers.
Chief Superintendent Ellie Bird, Scotland divisional commander, said: "Emily is truly deserving of this award and without her brave actions the outcome could have been so much worse."