When people ask which is the world's largest online sportsbook and casino, the most useful answer is rarely a single name. Size can mean market value, reported online revenue, how many people visit a brand's site, or how many active customers an operator serves. Each metric gives a legitimate but different view of scale. This article gives a short, evidence-backed answer, explains the common metrics used to rank operators, and offers a practical framework and checklist so you can decide which measure matters for your purpose. It draws on recent public-market coverage, company results, and traffic rankings to keep the guidance concrete and verifiable.

Flutter leads on market-cap measures after its 2024 NYSE listing, but 'largest' depends on your metric.

Traffic lists like Similarweb show different leaders such as bet365, illustrating how reach and revenue can diverge.

Use a simple checklist to compare market cap, revenue, and traffic before naming a single largest operator.

Quick answer: Which is the world's largest online sportsbook and casino?

Short answer, with one important caveat: by market capitalization and, on many reported revenue measures among public, online-first groups, Flutter Entertainment is the most defensible candidate for the world's largest online sportsbook and casino following its 2024 NYSE listing, though other operators lead on different measures.

That concise conclusion depends on how you define largest. If you mean market value, Flutter's public listing and market cap put it at the top of the list. If you mean site visits, a different set of brands appear near the top of web-ranking lists. Private companies add further complication because their most recent financial detail is sometimes not public.

quick data-source checklist to compare operators

Company name
Metric to check
Source
Date

Use one reliable source per metric

This quick answer follows public-market coverage and company reporting that place Flutter prominently among global online operators according to market value and reported online revenue.

How we measure 'largest' for an online sportsbook and casino

When people ask which operator is largest, they are usually asking about one of four things: market capitalization, online revenue, active users or customers, or site traffic. Each metric measures a different kind of scale and answers a different question about an operator's market position.

Market capitalization is the public market value of a listed company and is useful when you want to compare corporate value across public groups. Market cap reflects investor expectations and is updated continuously, but it does not directly measure sales or site use.

Online revenue shows the cash flow generated from online operations. This is the most direct measure of how large an operator's online business is, but disclosure formats vary and some groups report combined retail and online numbers in ways that require careful reading.

Active users, registered customers, or daily active users give a view of the audience and engagement. These figures matter if you care about product reach or monetization potential, but they are sensitive to definitions and the geographic mix of customers.

Site traffic, measured by third-party tools, captures visits and behavior on a brand's site or app. Traffic is useful to understand consumer interest and reach, but high visits do not always translate into the highest revenue or market value.

Finally, private operators can limit direct comparisons because their public disclosures are less frequent or differently detailed than listed groups. That gap makes it harder to update head-to-head revenue or profit comparisons for the latest fiscal years. Industry market size reports can provide useful context for scale online gambling market reports.

Financial leaders: market value and reported revenue among public groups

Public-market coverage after 2024 makes Flutter Entertainment the most notable candidate on the market-cap measure; its 2024 NYSE listing and resulting valuation put it at the top of public comparisons, which is why market-cap based lists commonly place Flutter first Reuters report on Flutter's NYSE debut. See market-cap lists for reference largest gambling companies by market cap.

Funded Plays Challenges

Compare operators

Flutter's full-year reporting for FY2024 also places it at or near the top of the sector for online revenue among diversified, online-first operators; careful readers should consult the company financial results for the detailed breakdowns and accounting notes Flutter full-year results.

In the U.S. market, DraftKings remains one of the largest online sportsbook players by revenue after reporting record full-year results for FY2024; that performance underlines its scale in the U.S. market and why revenue-based comparisons often put DraftKings among the leaders DraftKings FY2024 results.

Entain is another major public group to watch: its 2024 annual report shows a large, multi-brand online portfolio that keeps it among the global leaders by corporate scale and product breadth Entain annual report 2024.

When using financial metrics, the best practice is to look at market value and recent company filings together so you capture both investor perception and actual reported online business performance.

Traffic and audience: when site visits matter more than market cap

Third-party rankings based on site visits tell a different story than market-cap lists. Traffic measures are often the best way to identify which brand or site attracts the most daily interest from users, which can matter for user acquisition and product reach.

Similarweb's 2025 rankings show that bet365 ranks among the most visited sports betting sites globally, illustrating that web traffic leaders can differ from market-cap or revenue leaders Similarweb top websites ranking.

High traffic does not necessarily mean the highest revenue. Conversion rates, product mix, regional regulatory taxes, and monetization strategies all influence how visits translate into income. In short, a site can be very popular but still report lower revenue or market value than a more narrowly focused, higher-margin operator.

Traffic-based rankings are particularly useful if the reader cares about brand reach, marketing performance, or which products users are most often visiting. They are less reliable for answering investor-style questions about corporate value.

Why private operators complicate 'largest' comparisons

Private operators complicate comparisons because they often provide less frequent or differently formatted financial detail than listed companies. That gap makes it harder to update head-to-head revenue or profit comparisons for the latest fiscal years.

For example, bet365's last available annual results for 2022/23 show multibillion-pound online scale, but newer company-level financials for 2024 and 2025 are not publicly available in the same way, which limits direct comparability against public groups bet365 annual results 2022/23.

Check the checklist and verify operator size

Use the quick checklist in the 'Quick checklist' section to compare public filings, traffic rankings, and regulator disclosures before drawing conclusions.

Compare operators

Because private operators do not publish the same cadence of investor disclosures, analysts often rely on third-party traffic tools, regulatory filings in specific markets, or periodic corporate statements to estimate scale. Those signals are useful but carry higher uncertainty than continuous market-cap or audited public filings.

When private-company detail is missing, it is sensible to treat traffic and regulatory metrics as indicators rather than definitive proof of who is largest by revenue or market value.

A practical framework to decide which 'largest' metric matters to you

Choose a starting question: are you asking from an investor perspective, a user acquisition perspective, a product reach perspective, or a regional market comparison? Your goal should determine which metric matters most.

If you care about corporate value and investor comparisons, prioritize market capitalization and recent audited results. If you care about which brand most users visit, prioritize site traffic and user metrics from third-party tools.

Step-by-step, a simple framework is: 1) define your priority, 2) collect market-cap or audited revenue as appropriate, 3) check traffic and user metrics for audience reach, 4) adjust for regional differences such as taxation and regulation, and 5) triangulate findings across sources for a balanced view.

Minimalist 2D vector of stacked corporate reports with a magnifying glass over simplified financial tables in Funded Plays colors for online sportsbook and casino

For example, market-cap or investor-focused comparisons use the latest public valuations and company filings. Revenue-focused questions rely on recent full-year reports. Audience questions use traffic rankings and active user counts. Combining a few measures yields a more stable answer than relying on a single metric.

Common mistakes and pitfalls when naming 'the largest' online sportsbook and casino

An easy error is using a single metric to name the largest operator. Traffic, revenue, or market cap each tells a different story, and none alone covers every angle. Treat single-metric claims cautiously unless the metric is exactly the one you care about.

Another common mistake is confusing a single brand with a corporate group that owns multiple brands. A corporate group may include several popular consumer-facing brands but be reported in filings as one company, so make sure you compare like with like.

Promotional language from any provider can overstate scale. Cross-check claims with public filings, regulator disclosures in operating markets, and independent traffic tools to avoid being misled by marketing headlines.

Practical examples and scenarios: choosing the right metric for common questions

If you are an investor who wants to compare corporate value, market-cap leadership after public listings is the most relevant signal; Flutter's 2024 NYSE listing and subsequent market valuation is the clear example for that scenario Reuters report on Flutter's NYSE debut.

If you are a user who wants the site with the biggest user base right now, consult up-to-date traffic rankings because these show where people are visiting most often; Similarweb's 2025 sports-betting category highlights bet365 among the most visited brands globally Similarweb top websites ranking.

What is the world's largest online sportsbook and casino?

By public-market measures, Flutter Entertainment is the most defensible answer due to its 2024 NYSE listing and related market-cap position, while traffic leaders like bet365 lead on site visits and regional leaders vary by market.

If you want to understand U.S. market scale for potential partnerships or product launch decisions, look at recent revenue reporting for U.S.-focused operators; DraftKings' FY2024 results are an example of a public disclosure showing large U.S. online revenue DraftKings FY2024 results.

These scenarios show why the question you ask should dictate the metric you check. A single operator can lead on one measure and not on another, so match the metric to your objective.

Quick checklist: how to verify claims about the largest online sportsbook and casino

Documents and sources to check quickly:

Company annual reports and investor presentations for audited revenue and financial detail.
Market-cap data from financial markets for listed companies and revenue trackers such as the Commercial Gaming Revenue Tracker.
Third-party traffic tools such as Similarweb for site visits and reach.
Regulator disclosures in key markets for operating metrics and licensed activity.

Simple cross-checks to run: compare market cap, compare most recent annual or quarterly revenue, and compare traffic rankings. Always note whether a company is private and whether you are looking at a brand or a corporate group.

Wrap-up: the short, evidence-backed answer and what to remember

In short, the most defensible answer by public-market measures is Flutter Entertainment, which became the world's most valuable online betting operator following its 2024 NYSE listing, and its FY2024 reporting places it at or near the top on some online revenue measures Reuters report on Flutter's NYSE debut.

At the same time, traffic leaders such as bet365 appear at or near the top of web-ranking lists, underscoring that the answer changes when you prioritize site visits over market value Similarweb top websites ranking.

Use the checklist and framework in this article to match the metric to your purpose, check company filings and traffic rankings, and remember that private operators and different accounting approaches make a single definitive ranking difficult.

How is 'largest' defined for online sportsbooks and casinos?

Largest can mean different things: market capitalization, online revenue, active users, or web traffic. Each metric answers a different question about size and reach.

Does higher site traffic mean higher revenue?

Not always. Traffic shows interest and reach, but revenue depends on conversion, product mix, regional taxes, and monetization.

Can private companies be the largest even if not public?

Yes, private operators can be very large, but limited public financial detail makes direct comparisons harder and more uncertain.

If you need a quick next step, pick the metric that matches your goal and run the checklist in this article against the operators you care about. For investor questions, check market-cap and audited filings; for product reach, check traffic tools; for regional comparisons, look for regulator disclosures and market reports. This approach will give you a clearer, defensible answer than relying on a single headline claim about which operator is largest.