Revenue fell 42% year-on-year to £11.9m ($14.6m), with Smarkets generating £20.6m in 2017 and £24.9m in 2016.
Gross profit also fell 58% to £7.3m, with cost of sales up 35% to £4.6m. Overall, the company recorded an £8.9m loss for the financial year.
That said, the number of customer deposits held rose 71% to £28.8m and trading volume increased 46%.
Smarkets CEO Jason R. Trost said: "I'm incredibly excited about 2019 and I want to thank everyone for their contribution and commitment to getting the company into such a great position during the last year.
"Smarkets can push ahead with expanding our activities; focusing on the more profit-generating areas of our business and more efficiently monetising our growing trading volume, as well as taking the company out into the huge sportsbook sector and new international markets."
