The 15-year-old had been attending a presentation led by Mo Timbo from PH Church Hull and had gone outside to get some fresh air when he was stabbed by two youths.
He suffered serious injuries to his arm and back and was rushed to a nearby hospital where he underwent emergency surgery following the attack on Saturday evening.
Mr Timbo, 31, has spoken of the moment he realised the teenager was seriously hurt, as he continues to travel across the country to educate children on the dangers of knife crime and violence.
He said: "I was literally at the point in the presentation where I speak about the moment I was stabbed and the boy ran in shouting 'I've been stabbed'.
"At first I thought he was mocking the situation and then I saw the blood coming from him and everyone just went into panic mode."
Mr Timbo had travelled to Bedford on Friday for a weekend of presentations and had met the teenager that night.
He said: "He was so touched by the presentation I had given that he went away that night and came back the next day with an anti knife crime song he had written.
"I got him to perform it as well, which was absolutely great.
"Shortly after he had performed the song he went outside to get some fresh air and that is when he was approached by two boys.
"They asked him where he was from. He told them he was from north London and that's when they pulled out a huge machete and stabbed him in the arm and back."
The teenager is still recovering in hospital from the attack and has lost some feeling in the arm in which he was stabbed.
Mr Timbo said the events that unfolded on Saturday night have made him even more determined to tackle violent crime.
He said: "If I wasn't inspired before, I definitely am now.
"For me, this just makes me even more committed and I look at it as a challenge.
"This is my heart beat and we are taking this campaign to another level."
Mr Timbo is part of the #NoMoreKnives campaign, which was launched in Hull in partnership with Humberside Police and the RICH Foundation.
The campaign aims to educate children on the dangers of knife crime and challenge the perception that carrying a knife is normal.
The campaign has already educated thousands of pupils in schools across the Humberside Police area.
Mr Timbo said: "I feel so proud to be part of the campaign.
"I can use my experiences of growing up in London and getting embroiled in gang culture to really make a difference.
"I turned my life around and these children can do the same.
"Every time just one student comes up to us to thank us for what we are doing it really spurs us on."