Pre-tax profits at the group jumped 46 per cent last year to £2.26m, up from £1.55m in 2014.
It follows Leon’s heavy investment in its 600-strong workforce, including offering free meals, paid breaks and a 60 per cent discount on food while off-shift.
Co-founder John Vincent said: “Every year Leon just grows bigger and stronger. We want everyone to eat well and be well, and we start with our own team members, who are like family to us.”
Hospitality chains including Zizzi and Cafe Nero have faced criticism for cutting staff perks following the introduction of the National Living Wage (NLW) in April.
Leon extended the NLW to all workers in January, and has trained baristas in the martial art of Wing Tsun – which it claims has reduced staff stress and sped up coffee making.
The booming healthy fast food chain secured £11.5m funding from HSBC last year to allow it to ramp up expansion plans in the UK and worldwide.
It will make its European debut in Amsterdam’s Schiphol airport this summer, and is aiming to launch a site in Florida in summer 2017, according to BigHospitality’s sister site MCA.
Vincent said: “We have always seen fast food as an international business and, like McDonalds back in 1971, have picked Amsterdam as the launch site for our European journey.
“The Dutch are almost as funny as the English so we’ll have to keep our jokes as fresh as our food.”
Leon was founded by Vincent and Henry Dimbleby – the son of broadcaster David Dimbleby – in 2004.
As part of its ongoing mission to prove that fast food can be healthy, the group has cut the sugar content in its lemonade by 20 per cent and is one of a handful of chains to sign up to Jamie Oliver’s sugar tax.