The investment will more than double the number of cadets in London, from 235 to 500 and ensure every borough has a fire cadet unit.
In total 15 new London Fire Brigade run units will be created over the next two years in areas including Barnet, Camden, Hillingdon and Wandsworth.
"The London Fire Brigade is doing fantastic work with young people across London through its fire cadets programme and I am delighted that this additional funding will mean that they can equip over 500 young people - from every community and background - with essential life skills, as well as help to develop some of the firefighters of tomorrow," said Khan.
"Youth services such as the Fire Cadets are vital for Londoners and I will continue to do everything in my power to fund and support the fantastic programmes, schemes and charities that are making a real and lasting difference to our young people."
Activities that cadets take part in include fire safety, first aid and firefighting skills. They are aimed at boosting confidence as well as communication and employability skills.
Since the units first launched in the capital 50 young people have gone onto work as firefighters and other roles with the London Fire Brigade.
Fantastic news for our @LFBFireCadets! The @MayorofLondon is investing £1.1M to create positive opportunities for young people in every #London borough. Now is a great time to get involved in becoming a Fire Cadet or a volunteer https://t.co/OkTUvVLHoS pic.twitter.com/0Q96FrJZk0— London Fire Brigade (@LondonFire) February 13, 2019
The brigade is also keen to use the cadet units to boost diversity in its recruitment. Currently more than half of cadets (55 per cent) are girls and 49 per cent are BAME (black, Asian and minority ethnic).
"The funding will mean many more young people in London will have the opportunity to become a fire cadet. Our scheme gives young people the opportunity to gain a BTEC qualification, improves confidence and encourages them to take an active role in their communities," said London Fire Brigade commissioner Dany Cotton.
"Over half of our cadets are young women showing that London's youth are challenging stereotypes of the fire service. The expansion of our programme will help break down barriers further and hopefully lead to more women becoming interested in the fire service in the future.
The funding for London's fire cadets is one of a number of youth work investments Khan has made to help divert young people away from crime.
This includes his £45m Young Londoners Fund, which offers positive opportunities for young people and was set up to counter cuts to youth services in the capital.
Last September the fund handed 36 youth projects, including arts and sports initiatives, £2.6m worth of funding.
In July last year £750,000 was handed to schools to provide summer activities and ongoing support to young people and in May last year 34 projects aimed at protecting young people from knife crime shared £1.15m through the fund.