South Korean law enforcement is actively investigating domestic users of Polymarket, the blockchain-based prediction market platform, on illegal gambling charges. The Gangwon Provincial Police Agency's Cyber Investigation Division, acting at the request of the Korean National Police Agency, is tracing users' on-chain cryptocurrency transaction histories to identify individuals and is issuing summonses sequentially. Completed cases are expected to transfer to the Chuncheon District Prosecutors' Office. Users potentially face fines of up to 10 million Korean won (approximately $6,495 USD), and criminal penalties could be more severe depending on how courts ultimately classify the activity under South Korean law.

The investigation targets South Korean residents who traded on the platform, not Polymarket itself. That distinction matters: Korean criminal law explicitly extends gambling prohibitions to overseas platforms, meaning a resident using a foreign-hosted site can be prosecuted at home. To understand why the prohibition reaches that broadly, it helps to know what gambling South Korean law does permit. Legal betting is confined to state-run channels: Sports Toto (established under the National Sports Promotion Act of 1997), the Kangwon Land casino (the one venue where Korean nationals may gamble domestically), and state lotteries. Everything outside those channels, including foreign-hosted platforms, falls within the prohibition. Police are using Polymarket's public blockchain infrastructure as evidence rather than a barrier, tracing cryptocurrency transaction histories on the network, which operates on Polygon and settles in USDC according to platform documentation, back to wallet addresses they can connect to real identities through KYC records held at registered domestic exchanges. No court has yet ruled definitively that using Polymarket constitutes gambling under South Korea's criminal code, so users currently occupy an unresolved legal position but one with active enforcement risk.

The Polymarket probe does not stand alone. It arrives amid a broader South Korean regulatory escalation against the crypto sector in 2026. In January 2026, authorities dismantled the Hawanchigi network, a $113 million money laundering operation with crypto links. Also effective January 28, 2026, the Google Play Store began enforcing a requirement that foreign crypto applications hold Virtual Asset Service Provider (VASP) registration in South Korea, effectively blocking unregistered apps from that distribution channel. Legislators simultaneously introduced the Digital Asset Basic Act for consideration, targeting foreign VASPs and stablecoin issuers. Those developments build on the Act on the Protection of Virtual Asset Users, which entered into force in July 2024. Together, they establish that the action against Polymarket users is part of a coordinated regulatory posture, not an isolated initiative.

Han Chang-bo, a representative lawyer at Law Office Jonjung and a former gambling prosecutor, confirmed that Gangwon police are currently treating Polymarket activity as gambling under South Korean law. He urged users to "exercise caution," warning that the investigation's outcome could shape future regulation of prediction markets and broader decentralised finance platforms in the country. A separate regulatory process is also underway: the Korea Communications Standards Commission opened a formal review to determine whether Polymarket constitutes illegal gambling content, following a complaint filed with authorities. An unnamed KCSC official said the platform "differs from a typical gambling site and therefore requires a detailed review," while acknowledging it "could still be viewed as a new type of gambling-related site." Legal expert Jin Hyun-soo warned that access to Polymarket could be blocked entirely if the platform continues operating without reviewing domestic regulations.

South Korea sits inside a global pattern of tightening oversight around prediction markets. Eight countries have already formally classified Polymarket as an illegal gambling platform and blocked access: France, Germany, Italy, India, Brazil, Ukraine, Australia, and Argentina. Several US states, including Minnesota, Wisconsin, and Nevada, have issued cease-and-desist orders or filed lawsuits over sports-event contracts on prediction market platforms. Despite this mounting list, Polymarket remains accessible in South Korea and offers Korean-language service, a factor observers say brings the platform within domestic enforcement scope. Legal analysts note that a localised Korean-language interface is likely to be treated by regulators as evidence that the platform is actively targeting domestic users.

The scale of what is at stake commercially makes the South Korea case worth watching closely. Polymarket's monthly global volume reached $21 billion in January 2026, according to TRM Labs, up from $1.2 billion in early 2025. The platform set a single-day trading record of $425 million on February 28, 2026, and active unique wallets tripled over six months to roughly 840,000 in February 2026. Full-year 2026 global prediction market volume is projected at $240 billion, according to Bloomingbit. South Korea is the 12th-largest crypto market globally, and the Korean won consistently ranks among the top two fiat currencies worldwide by crypto trading volume. The figures suggest that losing access to Korean users would represent a meaningful commercial setback for any prediction market operator. Heechang Kang, co-founder of Four Pillars Research, noted that "prediction markets could be a very big opportunity in the Korean market," while cautioning about implementation challenges given the regulatory environment.

The enforcement mechanism used here carries implications well beyond South Korea. The case offers a proof of concept for regulators in India, Nigeria, and similar markets with large retail crypto bases and underdeveloped prediction market frameworks: blockchain transaction histories, read with analytics tools, can identify users of a pseudonymous foreign platform without any cooperation from the platform itself. Several African financial intelligence units have begun piloting Chainalysis, the blockchain analytics platform, for similar investigative purposes. The South Korean case demonstrates that user-level prosecution is operationally viable without shutting down the underlying protocol. Legal observers note this marks a departure from earlier enforcement approaches that focused on seizing centralised platforms, though that characterisation reflects analytical commentary rather than a formal finding in the current proceedings.

The investigation remains active as of June 5, 2026. The legal question of whether prediction market trading constitutes gambling under South Korean law will likely be tested formally once cases reach the Chuncheon District Prosecutors' Office. That determination, when it comes, will carry weight beyond South Korea's borders, offering one of the first significant judicial readings of where blockchain-based prediction markets sit within traditional gambling statutes in a major Asian market. For South Korean users currently active on the platform, the most proximate guidance remains the one Han Chang-bo offered plainly: exercise caution.