The research, released ahead of Father's Day by Zonal Retail Data Systems and CGA Peach, shows that 18% tend to use a venue's own website, while 10% book through an outside site and 3% use an app.
The figures show online engagement highest in London where 48% prefer to book online.
Furthermore, Google says that restaurant-related online searches are up 17% year-on-year and 80% of people who research a venue online want to make a booking there and then.
Zonal research of members of the Publican's Morning Advertiser's MA300 multiple operator business club found that more than a third of operators that had websites didn't have online booking facility.
Zonal’s marketing and sales director Clive Consterdine said: “With the sharp growth in online commerce, consumers expect to have instant access to all purchases, including dining out and with 30% of online table bookings made when a venue is closed, a responsive online booking facility is vital if operators want to get a larger slice of the cake.
“Our roadmap over the last five years has been focused on the predicted growth in mobility, as people become more familiar with using their smartphones as part of their eating out experience. Operators can’t afford to wait; those with responsive online booking facilities that respond to customers’ wants and desires will tap into their need for instant access and ultimately win the bookings war.”