The accolade is an impressive one, considering the site was launched in October 2015.
It has over 500,000 users, its own podcast and a YouTube channel, allowing players to buy and sell shares in footballers.
The operator works in a fashion that allows Football Index to take commission off every trade, rather than a player vs bookmaker scenario.
Adam Cole, Football Index CEO, said: “This is a huge honour for us that recognises the brilliant growth of Football Index, and the product we’ve developed.
“Given the UK’s powerful tech sector, climbing to second place is a fabulous result, establishing us as one of the UK’s most significant fintech success stories.”