William Hill suffered decreases in both revenue and profit for 2015.
Net revenue fell 1% year-on-year to ¬£1.59bn, reflecting the lack of a major football tournament, a lower average number of shops, less favourable sporting results and "extensive work to refocus the Australian business".
Operating profit dropped 22% to ¬£291.4m, while profit after tax was down 8% to ¬£189.9m.
Operating profit was up 2% excluding c¬£87m of additional UK gambling duties.
The firm reported ¬£300.9m of operating cash flow, compared to ¬£368.2m in 2014.
Net debt for covenant purposes was down to ¬£488.2m from ¬£602.8m, equivalent to 1.3x EBITDA.
Online, which accounted for 35% of overall company revenue, enjoyed a 4% increase in net revenue to ¬£550.7m.
Online operating profit fell 29% to ¬£126.5m, which the firm said was driven by an additional ¬£66.4m in UK point-of-consumption tax following its introduction on 1 December 2014, adding that operating profit would have grown 9% without the cost.
Retail, which accounts for 56% of group revenue, saw net revenue decrease 2% to ¬£889.5m.
Retail operating profit fell 11% to ¬£171.4m, which the firm said was driven by an additional ¬£19.1m in machine games duty, the rate of which increased from 20% to 25% on 1 March 2015.
Without the increased duty, operating profit would have declined by only 1%.
William Hill Australia net revenue was down 20% on a statutory reporting basis and 11% on a local currency basis.
Australia operating profit fell 46% on a statutory reporting basis and 41% on a local currency basis.
William Hill US net revenue was up 12% on a statutory reporting basis and 5% on a local currency basis.
US operating profit was down 5% on a statutory reporting basis and 11% on a local currency basis.
William Hill CEO James Henderson said: "In the last 12 months we have made substantial operational progress against our three strategic priorities of omni-channel, technology and international.
‚ÄúIn technology terms, online now has a platform that allows us to deliver rapid and frequent innovations to customers, further differentiating our offering.
"We are also now preparing to roll out our proprietary self-service betting terminal in retail.
"This is an important part of our omni-channel strategy and enables us to bring the best of online to our shops.
‚ÄúAs one of the largest scale businesses in gambling, the board is confident in the outlook for the year ahead and believes the group is well placed to deliver on its growth strategy.
‚ÄúWe have reviewed our priorities for capital alongside our strengthening balance sheet and our continued good cash generation.
"Together, these underpin our decision to announce a share buyback alongside our ongoing investment to grow the business.
"In addition, the board has increased the dividend payout ratio to around 50% of adjusted earnings, reflecting our focus on delivering value for shareholders.‚ÄĚ