The Grand National, which attracts bets from regular gamblers and those who never normally place a bet, took place this year at a time when Britons are struggling with a cost-of-living crisis amid elevated inflation and high borrowing costs.
The event on Saturday was also briefly delayed by animal rights protesters at Aintree.
Flutter Entertainment, owner of brands Sky Bet, Betfair (sportsbook) and Paddy Power, said total bets on the race across its UK and Ireland online brands were 10.9 million, slightly up from last year's 10.4 million.
Corach Rambler's victory as favourite cost Flutter a "seven-figure" sum, it said, adding it made some of that back on other bets.
William Hill had reported a turnover in the region of £200 million pounds for the Grand National last year.
"We're looking at numbers in line with last year, so no notable growth to report which was expected given the wider fiscal and regulatory headwinds in the UK at the moment," said William Hill spokesperson Lee Phelps.
The gambling group, whose non-US assets were purchased by 888 from Caesars Entertainment last year, runs online and betting shops across the United Kingdom.
Ladbrokes owner Entain said 18 per cent of its UK online customers backed Corach Rambler. Entain, which is set to report its first-quarter results on Tuesday, did not give further details.
Online revenue growth at British gambling firms has tapered off their highs and is starting to slow from pandemic times.
