And now he's ready to make his mark in his sport again – with Paris 2024 his long-term focus.
Niall, from Kingstanding, has become a doting dad, to daughter Nairobi and he's also stepped up his charity work, forming his own organisation to support those struggling in life.
"It's been a crazy few months," he says. "It's 100mph at the moment.
"I have become a father and it's a crazy feeling holding a baby who is your own flesh and blood.
"I hold her and it's just amazing.
"I'm juggling fatherhood with doing loads of charity work as an ambassador for Good Shepherd.
"And I have set up my own charity called Support Futures, for which I am chairman and trustee.
"I went to a knife crime event in Bilston where I met numerous people and it inspired me.
"We set up the charity and we are all affiliated now and getting grants.
"It's for 18-30-year-olds who want a second chance. They might be young offenders or homeless.
"It's for anyone who has not had the best of starts who want to push themselves and get a better life. Everyone deserves a second chance so why not?
"So here I am, a dad at 24, chairman of a charity and ambassador of another.
"But I'd rather be too busy than sitting at home not doing anything.
"I'm enjoying life and feel blessed. I am the happiest I have ever been."
"Being a father I am learning a lot ," he adds. "Luckily my dad (boxing coach Paddy) is great and anything I need, he's there.
"I am fortunate that I can go to him and say: 'What do I do here!?'
"With the charity I have a great team behind me, my parents, as well as GB Boxing."
As life, albeit cautiously, starts to get back to normality, Niall's focus in back on boxing and he is now building up to a massive three years in the ring.
"I went to Tokyo as a sparring partner for the GB Olympians and that was a great experience," he says.
"I loved every minute out there and now I'm ready for my own challenges.
"The World Championships are in Serbia soon and it's the start of a new cycle with the aim of the Olympics in Paris in three years time.
"We have the Commonwealth Games next year as well so the worlds will set us up for the years to come.
"I want to perform well in Serbia. It's about progression.
"Success at the worlds gets your name out there so when you go to the Commonwealth Games next year people would think 'There's Niall Farrell'. It's like a snowball effect in the best way possible.
"I am training hard. I'm loving the tough training because what you put in, you also get out.
"That's what I've thought since back at school. If you want anything in life, you have to work hard for it.
"You see that with the Great Britain camps - we are surrounded by great talent but also hard workers."
While the worlds are the focus right now, attention will then turn to Birmingham 2022.
And for Niall, the Commonwealth Games will be a moment to savour.
"I have not boxed in Birmingham for about six years," he said. "I can't wait to bring my die-hard supporters, who come to places like Croatia with me, to Birmingham.
"I'm a Brummie born and bred and proud to be so. I'm so happy the Games are in Birmingham and I can't wait to perform. You will be able to hear my fans up in Liverpool!"
He added: "But you can't overlook anything. I'm focused on the worlds first and foremost.
"It's an exciting time ahead. There's light at the end of the tunnel in terms of Covid, hopefully, and it's time to get the ball rolling.
"It's going to be a great time. Amateur and professional boxing is thriving in the UK at the moment."