The extra cash will be put towards building up its ski trips and moving into new road cycling holidays.
The money came from Seedcamp, a London-based investment fund, as well as former executives from the likes of Google, Lastminute.com and eBay.
The London Co-investment Fund, backed by the mayor, also participated.
Boris Johnson said: “London’s tech and science sector is flourishing and the city is a hotbed of talented and ambitious people buzzing with exciting ideas who are setting up new companies in their droves.
“I am delighted that the London Co-Investment Fund is helping companies like Much Better Adventures to make their ideas a reality and deliver jobs and growth for the capital.”
The travel company, which offers holidaymakers the chance to connect with local independent specialists, started life in 2012.
Alex Narracott, Sam Bruce and Guy Bowden founded the business out of a rented chalet in the French Alps.
Bruce, who is one of this year’s TTG 30 Under 30, said: “Our customers have been asking us to expand into new markets and this investment allows us to launch the first online marketplace for cycling holidays which we’re very excited about.
“It’s a multi-billion pound market with over 25 million overnight trips taken each year in the EU alone, but much like most of the active holiday industry, it’s incredibly fragmented and poorly served by existing online platforms.”